first of all people would be really sad that their bitcoin price will not grow at all besides that investors would quit from bitcoin so the price would be dumped alot
But if the Bitcoin price doesn't grow at least 2x with each halving (which most certainly won't happen), each halving will be a new turn in the downward spiral that Bitcoin may get trapped in. Mathematics (or rather its detachment from reality) would mercilessly and relentlessly kill Bitcoin within a decade, i.e. in 2-3 halvings...
Unless they get canceled, of course