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!

yes all correct and potential future truth predictions
with regards to hash rate it is possible that an increasingly centralized distribution becomes very decentralized once more over time
if it is not seen as profitable or actually profitable for centralized mining pools to make payouts based purely on transaction fees depending on volume then individuals are more likely to be solo mining once more directly to support the network security
this is the likely scenario for xaucoin with individuals hopefully solo mining onto the wallet once more to support the network process transactions and secure their investment holdings
as the block reward is dropping xaucoin could present an excellent opportunity to use old usb block eruptors or usb antminers to support the network through mining directly onto the wallet
will future generations be solo mining onto the Bitcoin network with old s3 or s5 hardware again simply to support the network and process transaction which is an increasingly unlikely scenario over time although something to think about
what was it satoshi had said about being certain of very high future transaction volume or of their being no transaction volume at all