Bitcoin transactions settled instantly without confirmations: Can this be reality one day ?
I think there will always be the issue of double spending if you accept it instantly.
The details are in the paper, but I think that's one of the main inventions of Bitcoin. Removing that wouldn't make too much sense unless something remarkably new came along and allowed that to happen.
The constants that Satoshi chose (10 minutes on average, etc), work remarkably well, and that's actually quite difficult to achieve, so I don't think that will change.
For faster payments we already have lightning which is pretty cool.