He’s replaceable IMO, term is fine.
Yes, by the time his contract is done, one of two things is likely to happen: either he'll have put everything together and take his game up to the point where he can be a legit 2 C; or other players within the CLB organization will have emerged as better centers and supplant him in the lineup.
If the latter happens when Roslovic is still in year 2 of his contract and if the team isn't in the playoff hunt, it also gives them the option to trade him for assets at the deadline if they're not going to extend him.
So it's really a no-lose situation.