This is never going to happen, there are good reasons why it does not happen. It would bloat the chain massively and introduce other security assumptions making Bitcoin more vulnerable.
It can be a hurdle in some cases like when the buyer needs instant delivery but seller makes him wait till confirmed.
Use the Lightning Network if you need instant confirmation times, the end.
We have an off-chain solution to settle instant transactions that is already available, but an on-chain instant confirmation of transactions, although possible by tweaking the code of the Bitcoin core program, is dependent on the judgment and decision of the Bitcoin developer. Whether the on-chain instant confirmation can be implemented or not is for us to see.
The developers don't decide, the users do.