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.
Developers are users too, technically, aren't they? But do users(excluding developers) write the code for Bitcoin development? There is consensus, yes, but the consensus chooses from the path the developers offer... I think you can imagine the whole picture of decision-making from that.
Bitcoin transactions settled instantly without confirmations: Can this be reality one day ?
Since you used "settled" and not confirmed well this is very much possible, before people learnt how to double spend and all that...BTC deposits were settled almost immediately on some exchanges and gambling platforms as that 2/3 confirmations was pending this reflected on our accounts but a withdrawal was not possible until the required confirmations was attainable...but if it's confirmations getting instantly confirmed if not lightening network no because by design network wasn't developed this way...
I think you are mistaken settled as being sent. They are different. In Bitcoin terminology, settled means irreversible because they have enough confirmation, which is impossible for the current Bitcoin network to be called instant.
Meaning it is impossible to settle a transaction without confirmation, and it needs enough confirmation, not just 1.