Bitcoin has the first mover advantage and massive adoption, no altcoin even comes close. To overtake bitcoin we'll need something that is as revolutionary as bitcoin is to the fiat/banking system. Monero is not that.
If minor improvements is all that it takes, we will soon enough see monero outcompeted by other currencies. Who's to say there won't be a zerocash type currency coming out where the parameteres are generated in a trusted manner? Suddenly everyone will flock to "the next big thing". Switching quickly between currencies like that means the storage of value is lost, nobody would use USD if they knew next month USD 2.0 will come out and their USD 1.0 will quickly decline in value. And then month after that USD 3.0 comes out with same result. This would be horrible for the ecosystem (and that without mentioning the huge costs of infrastructure change), and I don't think this will happen.
Monero serves a purpose, but for the majority of people the anonymity offered by monero isn't a revolution compared to bitcoin. Even if it was, bitcoin could implement it. That applies to any altcoin, too much is invested in bitcoin to let it be outcompeted. If there appears to be a serious threat, bitcoin will adapt.
It may turn out to be the case that bitcoin never goes anonym like monero. This could put a lot of pressure of it's back from governments that will instead be directed at monero and other anonymous currencies. Maybe that's a good thing.
Keep in mind that sidechains are coming, those could potentially make monero obsolete.
I realize this is swearing in the church, I like monero very much, but let's not get delusional. It's future success is not set in stone. I think at best monero can be a high liquid altcoin like LTC has been, and work as a complimentary currency to bitcoin. It may be, that bitcoin takes the spot as mainly storage of value, like gold is today. And that monero takes the spot as transactional currency. But it will never be the #1 crypto. That ship has sailed.
Bitcoin == Too big to fail ?
Oh goody. Lets prop up another flawed infrastructure because change is too costly.
In general, I agree, and I've said as much before, and its been stated elsewhere - the transparency of bitcoin is congruent with some fintech needs, and its eventual (if not extant) centralization is as well. An altcoin that fills the void that bitcoin leaves as bitcoin transmogrifies into Fintech Gold Backbone will need functions that complement it. Truly private transactions is one such complement. We'll see how the centralization battle goes.
And we're already witness to this implementation (XBT = backbone, altcoin with new function uses backbone as bridge) XMR.TO