What happens when there is so much halving that the reward for mining bitcoin is extremely low and the cost of verifying the blockchain for the miners exceeds the reward of their bitcoin?
Just like in every business the unsatisfied miners will leave and switch allegiance to other projects and mine them. There will be few miners to man Bitcoin chain and this will invariably cause mining charges to surge to meet up with the little block rewards. Conclusively, all that will make Bitcoin value hit the roof, with price so high that those who aren't buying will regret like those who didn't buy in 2010.