The underlying concept may be, but that depends how affordable hashing power is by then. If you can't make more than a block is worth, it's not worthwhile. Transaction fees on blocks these days seem to be at most about 1.5% of the block reward, and even then, mining is considered unprofitable for many. Of course, if Bitcoin is used more widely, the transaction fees will increase in volume (and thus in total value), too.

As for literally Bitcoin itself, I'd be very surprised if SHA256 isn't broken within the next hundred years, either by simply something no one noticed before, or by computers becoming powerful enough that brute-forcing SHA256 is negligable.

As for this coin? Let's hope to see it go up!