Block rewards are designed finite but also designed to end outside most peoples lives. So in short no one needs a solution. Block reward of 0 theoretically would be reached in 2140. Of course earlier halving will already have a similar effect BUT ONLY if the price does not at lest double every halving (4 year). Essentially this means bitcoin will allays run on inflation. The finite supply is a "lie" that just doesn't work the same way if the price per unite can simply multiply. You constantly add a smaller fraction of the total but suck out more and more value anyway. mining has never become cheaper if price/hash drops it just raises the hashing required to mine.
The people who hold BTC but dont use it pay (via inflation) for thous who use it so they have cheaper (still laughably expensive) transactions. They just dont care about that as long as price gains far outperform the inflation loses.
At some point it has to crash and wont recover because double-spends happened and the network can no longer be trusted which renders it useless.
If the price (real world purchase power not the price in USD) doesn't multiply for more than 4 years... the end is near. Likely the end would come before the 4 years are over.
historically hash rate drops the most 1-1.5 years before halving in sync with the price. it basically boils down to how good large miners are at managing risk. they need to have the money to keep mining while its not profitable. if a large player goes bankrupt it could create a chain reaction crashing the whole thing.
BTW, next generation blockchains like the XRPL have solved all of theses problems a long long time ago. The lead dev (ex btc dev) saw these problems ~10 years ago and it took them 1-2 years to come up with something better.
At some point it has to crash and wont recover because double-spends happened and the network can no longer be trusted which renders it useless. If the price (real world purchase power not the price in USD) doesn't multiply for more than 4 years... the end is near. Likely the end would come before the 4 years are over. historically hash rate drops the most 1-1.5 years before halving in sync with the price. it basically boils down to how good large miners are at managing risk. they need to have the money to keep mining while its not profitable. if a large player goes bankrupt it could create a chain reaction crashing the whole thing.
BTW, next generation blockchains like the XRPL have solved all of theses problems a long long time ago. The lead dev (ex btc dev) saw these problems ~10 years ago and it took them 1-2 years to come up with something better.