at this point it will be 2140 and I assume if its still around that there will be so much invested that it will be "too big to fail" (satoshi may be rolling in his grave). Also in the year 2140 I don't think anyone of us can begin to fathom what life will be like then.
2040ish will already be down to 0.2% per year from the 12.5% currently. 2140 is nonsense as that is just where the asymptotic limit reaches 1 Satoshi per block perhaps (I didn't bother to calculate it).
The incentives to mine are: newly created coins and the transaction fees. Even when all coins are mined, the transaction fees still belong to the miner.
Refuted that as being viable:
https://bitcointalk.org/index.php?topic=349869.msg3755466#msg3755466