Like this scenario: Team A has the ball and fumbles. Team B recovers the fumble, returns it a ways, and then it gets stripped and Team A recovers the 2nd fumble. Does recovering and returning the first fumble count as a possession Team B? They technically possessed the ball.

You also eliminate punting/punt block/punt return, which can be a major component of the game.

I think you have an interesting idea and you might be onto something. Considering the game clock is operated by a human, there is some merit to eliminating it's use.

Nope. Turnover on downs or points.

A blocked punt would be a turnover before the end of 4th down.

If teams trade interceptions or fumbles the "original possession" hasn't ended. It's possible to get points on the other team's possession.

5 points for hitting uprights on field goal attempt or 2 points on try after. Safer kick down the middle for fewer points or risky edge kick for more.

Mostly joking, but it would be kinda entertaining.

16 team playoff

Bugle Call is an automatic 15 points for the other team