Some clarification about Portugal's revolution of 1974 and why the comparison with Egypt may not be the best. First, the authoritarian regime of Antonio de Oliveira Salazar (1932-1968) rested on the armed forces as his power base, using as a popular base the Church (at least the hierarchy), the police and the paramilitary Legion, and of course a few families that controlled most of the wealth in Portugal as well as the colonies.
Political opposition was limited to Lisbon and Oporto - to some degree the northern parts - but with an outlawed Communist party, political opposition was weak and divided as was the case in Franco's Spain. Portugal's next door neighbor Spain under Franco was actually its best supporter, but the political and economic pressures on Portugal to end the dictatorship were coming mainly from France and to a lesser degree from England and Germany. This against the background of Henry Kissinger and the CIA expressing concern about the end of the dictatorship, but using US political support as leverage to demand military and foreign policy concessions.
When Marcello Caetano took over as prime minister and foreign minister in 1968, political opposition groups, except the Communists, were willing to give him a chance, although at the time the US privately assessed the new regime as a continuation of the Salazar-style authoritarianism. Portugal suffered labor unrest almost throughout the Caetano dictatorship mainly against foreign companies, while at the same time UN resolutions 2105 and 2107 called on international financial institutions (World Bank, IMF) as well as to NATO members not to provide any financial assistance to Portugal which would enable the Caetano government to prosecute colonial wars (at the expense of Zambia), and to engage in the recruitment and training of mercenaries in Guinea, Angola and Mozambique. In fact, the UN targeted Portugal along with South Africa, making it difficult for the Nixon-Kissinger team to defend Portugal.
Making it clear to Caetano that African decolonization was not necessarily an East-West conflict issue, therefore not a NATO matter, Kissinger used the UN resolutions to force military base concessions in the Azores. Lisbon also used the military bases to secure loans and support for its African colonies, and even permitted use of its air space during the Yom Kippur War as a bargaining chip. By spring 1974, the Caetano regime was feeling the pressure from its own population but also from the surrounding nations, which of course were led by France. Portugal's middle class had grown considerably and demanded reforms, as did the Europeans, adding decolonization of Portugal's colonies; policies with which the US considering beneficial because it too was convinced that Portugal under a liberal bourgeois government and decolonization would allow US corporations greater and direct access to markets from which they were not given full access.
When Caetano dismissed Antonio de Spinola, deputy chief of the armed forces, for advocating decolonization, junior officers sided with Spinola in forming the Movimento das Forcas Armadas, which led the revolution and called for massive restructuring of society as well as decolonization. Presumably under Kissinger's orders (after involvement in the Allende coup), the CIA tried to destabilize the Spinola movement which had very broad popular support. Europe immediately supported the Spinola movement and made it difficult for Kissinger and Nixon not to recognize the revolution. In short, the armed forces lit the spark and led the way to democracy in Portugal, just as the Egyptian armed forces recognized the futility of keeping Mubarak and asked him to leave so they can determine what kind of regime would be workable (not best, workable, or doable) for the country.
In Egypt's case, a) there is no middle class as had developed in Portugal by 1974; b) the political opposition comes mainly from the Muslim Brotherhood, although secular urban elements were significant in providing spark for the uprising; c) Egypt is not part of the European community of nations like Portugal was a candidate for membership, which necessarily entailed enormous pressure to democratize from the French and others in the early 1970s; d) unlike Portugal, Egypt's middle class is not sufficiently broad enough to sustain a regime in power and without a strong middle class you cannot have a middle class (liberal) regime; e) Egypt is a Muslim country whose political regime must necessarily evolve from its Islamic traditions and its history which has nothing to do with European Liberalism.
Let us keep in mind that in order to have liberal-bourgeois institutions it is essential that the country must have Liberals who invariably emerge from the middle class. This was a controversial argument that was made during the Chinese Revolution when Truman sent general George Marshall in China to forge some kind of a western-style liberal-bourgeois regime in a country with a handful of liberals and lots and lots of peasants whose interests and values had nothing to do with Western values and interests. The regime that Egypt will forge will reflect not some ideological model in a vacuum, but the realities of its social structure; and if it does not, it will not last long.
The path Egypt will follow is unknown, but it will be based on its history, societal structures, institutions--civilian and military--and current political waves that seems to be favoring the Muslim Brotherhood. The best policy for the US and others is to let the Egyptians handle their internal affairs, although the US and EU are already on record stating that the new regime must respect treaty obligations, international law, trade and investment agreements, existing alliances on which foreign aid is based; in short, policies that do not harm western foreign policy, strategic, and economic interests. Otherwise, Egypt can do what it wants with cultural issues, labor policy, social policy, expanding the police force, promoting tourism, etc.
The direction of Iran is probably closer to where Egypt may move, but perhaps not nearly as militant, given that the military holds most of the cards in the current political balance of power; a situation closer to that of Turkey actually.