if to remove ASIC, h/s will fall and production capacity will be less, it turns out the GPU will get 10-20 coins per day, which is not natural to date.
Well, how much will the coin cost?
"Production capacity" will be the same as with ASICs. The same amount of coins will be mined every day since it is enforced by the DAA, no matter how much hashrate is thrown at it.
I think you are very optimistic if you believe that one GPU will mine 10-20 MSR after the May 1st HF. That's not going to happen. I guess one GPU will mine less than 1 MSR per day. There is an abundance of GPUs out there which will start mining MSR as soon as it becomes profitable again. Orders of magnitude more GPUs than those which mined Masari previously. Hashrate follows price.
EDIT: I also want to use this opportunity to thank those who are selling me their MSR for 15-16k on TradeOgre. I sold appr. 25% of my stash from 20k to 22k (to lower my exposure) and I am happily buying back all of them now at a 25% discount. Keep them coming!