I, for one, am already curious as to who is going to be the first to challenge the status quo...
I will assume that you refer to the new status quo, the one created by a successful 1848 not just in Italy but also in other parts of Europe.
As far as Italy is concerned, I expect that the main internal challengers will be the conservative portion of Catholic Church and the big landowners, who are going to find support among the most conservative portions of the electorate; later on, there will be a challenge from the left, but I would expect it only after the living standards and the education have improved.
Note that I consider the end of temporal power, the separation of church from state or the abolition of the old ecclesiastical privileges will be beneficial for the Church as a whole. By the same token, the "most conservative portions of the electorate" includes a lot of persons who are not destitute, but are borderline, as well as the people who are seeing they are going to loose by the economic changes and, obviously, those influenced by church doctrine and condemnation of modernism.
The "left" will raise to challenge the new order in the medium to long term (in particular if the liberal-democrats act in a "reasonable" way, and can understand that economy is not - and should not - be a zero-sum game. However, even with the best of intentions from all, it is utopist to assume that the domination of the "big center" can last forever. As a minimum, I anticipate that towards the end of the economic boom the center-right will separate from the center-left, and it might happen even sometime in the 1860s, if something goes wrong or even if the generation which has fathered the "1848 miracle" will fail to rejuvenate. As a matter of fact, I would be quite happy to see an alternative to a big center who will inevitably become stodgy, and an alternation in power would certainly be much healthier. It is anyway better if this split happens only after the seeds of democracy have become well rooted, and the primacy of the law is uncontested.
Incidentally, I am reasonably convinced that democracy can only prosper among a reasonably educated population, which is why I am in favor of widening the franchise in steps: universal franchise is a worthy goal, but going in a single step from absolutism to universal franchise is a dangerous approach.
Looking to Europe as a whole, I would expect that both Austria and Prussia will not be enthused by the way the social and economic situation have changed. Regarding Russia, I tend to believe that they will react by increasing isolation from the west: a kind of cordon sanitaire to keep out new social ideas and paradigms. I may be wrong with regards to Russia anyway.