Miner/pool usually have strong financial incentive, so it's unlikely it'll happen on practice.
Why not? If miners will be paid for burning coins, then I think they will have an incentive to do that. Some people thought about Proof of Burn, it is definitely possible to encourage miners to burn some coins, if they could be rewarded somehow for doing that. And burning coins in Proof of Burn should be done as garlonicon said, then it is clearly connected with mining, and no additional outputs are needed, so it requires no additional on-chain bytes.
While it's possible, i don't see anyone would bother contact miner/pool when OP_RETURN exist and miner/pool might reject such request since they need to modify their software. Even for getting non-standard transaction included manually on block, there are only few pool which accept such request.
Just to add something else to the discussion: There are provably unspendable burn addresses which are not OP_RETURN outputs. The largest one I am aware of, which contains 2,609 unspendable bitcoin, is here:
https://blockchair.com/bitcoin/address/s-272edf45031dd498e7b3ae89e11ff21b. This address requires a pubkeyhash of 0 to be unlocked, which cannot be reached from RIPEMD-160, and so these coins cannot be spent.
I don't read RIPEMD specification or how it works in detail, but did you mean RIPEMD-160 output always higher than zero?