bitcoin would be never replace by another crypto currency because bitcoin getting too much power and bitcoin adopting is very much high and we know that bitcoin increase its price too much faster than other currency.
It is well known the potential of Bitcoin, but no matter how popular it is, it will not stop other technologies from appearing. But since Bitcoin continues with a good team of developers, there is no reason to worry, because in most cases the altcoins have improvements that can be implemented in Bitcoin. The problem is that it is not very easy to reach consensus on the network for this to happen.
Basically everything that altcoins have as flashy features can be implemented in Bitcoin as well, but there is absolutely no need for that as Bitcoin is working very well. The only thing people think could be better are the confirmation times. I can't really blame them for that as I understand that it can be annoying when you have to wait an hour to even get 1 confirmation in some cases. That's why larger blocks for now is the only thing that I see as a necessary update.
The devil is in the detail (as always)
There is no doubt that these impressive features can be implemented in Bitcoin too (provided it makes sense to implement them at all in the first place, of course), but so far Bitcoin cannot be even successfully updated to just cope with the growth in adoption. In other words, no one talks about making a huge jump ahead, it is more about taking a small evolutionary step to just live up to already existing requirements, as you yourself say. But even in that Bitcoin is failing, to our regret