I realize it's just one person's opinion but I do have respect when it comes to this one, so maybe it's an interesting topic to discuss.
1. Mining: The least efficient miners will face unprofitability because of the halving. Thus some miners are likely to turn off their equipment, leading to the drop of the difficulty rate, and mining remaining profitable to those who are still in the game.
In 2012, the hash power dropped after halving but later increased. That means, some miners left the industry while later in 2013, some later came into mining again as other new miners also join and this increase the hash power.
In 2016, this repeats it self again and the hash power increased.
So, after May, 2020 halving, it is certain that some miners will leave but we do not know what the price of bitcoin can be. The price is the determinant.
If the price does not increase, it is very likely that hash power will reduce but if the price of bitcoin later increase, then, more miners will join in mining again and hash power will increase.
So, it depends on the bitcoin price.