Miners revenue would be fees only. That wouldn't be enough to pay the electricity bills at the current hash rate. Either the fees would increase, or the hash rate would drop, or both.

Either effect could destroy Bitcoin, in my view. Lower hash rate reduces the coin's security; if it gets too low, the coin can't be trusted. High fees discourage users; if they get to high, users will switch to PoS coins or even back to credit cards.

If mining stopped "tomorrow", it would be an existential crisis for Bitcoin. However, it won't. Mining is set to gradually decrease over decades. If the value of Bitcoin doubles, on average, every 4 years, then that will offset the block reward halving.