That’s if you assume the price will not go up.
Lowering supply should increase demand assuming you lower it to the correct levels. If you lower it to less than the typical daily volume, price will rise. If you lower it to where it is still higher than demand, then what you are saying is a big possibility.
There is a calculated risk in messing with emissions. If you do it wrong, you set yourself up for exactly what you mention. But if you do it right, an increased price mitigates the lower emissions thus making it worth to mine. It’s not the number of coins that matter to the miner…it’s the value those coins bring. Increase the price on fewer coins is an acceptable trade off.