99.21875% will be mined in 20 years time. If electricity isn't very cheap by then and/or if bitcoin isn't worth hundreds of thousands of dollars, it's hard to imagine anybody wanting to mine then. How will transactions then be verified?
I think there is always a solution. Does bitcoin community has developers with ability to change code and submit new feautres? If yes, that's a number one resolution. Otherwise i heard switching to POS(Proof-of-Stake) system will give node runners a reward for approving transactions.