My proposal:
Both teams get the ball. 1st drive starts at the opponent's 10 yards line. If both teams score a td then they restart at the 20 yard line. So essentially each series gets starts 10 yards further away than the previous one.
Teams could choose to kick a pat or go for two. Or allow only 2 point conversions to end games faster.
The biggest issues with pretty much all fan proposals is they simply take too long.
If it wasn't clear already, the primary objective of OT for the NFL is to get the game over as quickly as possible. They have no interest in these short field, offensive dominated, transactions where teams go into 3, 4, 5 overtimes routinely (basically the college model). Anything longer than 5-10 minutes has very little value add.
Colleges have no issue doing this, because they largely exploit players for money. That doesn't work with NFL players who are already coming out of games banged up, aren't interested in playing another 30 minutes of football, and may have a short week or little recovery time before they have to play again.
It's why the NFL shortened its OT from 15 minutes to 10 minutes, and its why they allow for ties. It's also why they allow for the first possession team to win the game with a TD.
I think they'll make changes, but I'll be very surprised to see them make changes that involve lengthening the game in any capacity, which is pretty much guaranteed to happen if you shorten the field and put the defense at an extreme disadvantage (like in college). I also think any changes they make may ultimately only be for the playoffs instead of the regular season.