Usually this kind of thing doesn't end well i.e. the armed forces move in to fill the power vacuum, that or the State concerned collapses into anarchy. In this case I'm tempted to be a little more optimistic for a couple of reasons.
Firstly of all Nepal is a relatively small nation (geographically speaking) and the rioting seems to have been largely confined to the capital which means the instruments of civil administration outside of Khathmandu should be intact (well at least as much as they ever were that is).
But secondly and more importantly? As far as I can tell this riot wasn't a case of an uprising in support of one particular political, religious or ethnic group over another. This was a 'popular' revolt against the entire Neplaleze political class meaning that (in the sort term at least) none of the existing political factions in the country are in a position to exploit the 'revolution' for their own advantage. And I say 'popular' revolt because again, as far as I can tell about the only section of the society in Nepal that doesn't seem to have supported the students actions were the politicians themselves, their immediate families and backers! So having been thrown out? For now at least the 'garbage' has little chance of walking back in through the door and into office again.
Lastly the choice of a new PM was made quickly (even if in a somewhat unathodox fashion) and aplotically. What little I've read about Sushila Karki indicates she's not and never has been taited by allegations of corruption and as a former Spreme Court Judge she likely has the skill sets needed to organize a new government and fresh elections in due course.
Of course I might well be wrong about all of the above points but for now? As I said I'm inclined to be a little bit more optomisitc about Nepals future than I would be if this was another country facing a similar crisis.