No, overall rosters would stay at 26. Limiting pitchers means that usage needs to change so we'll get longer outings because the number of overall innings stays the same (and lots of teams have used 14 pitchers in recent years).
Can teams get by with fewer position player reserves? Sure. But the game is not really worse if the bench is larger. The IL is going back to 15 days for pitchers too so that will make it a bit harder to game rosters along with the 5-option per season limit.
I am not sure limiting the number per game will make any difference. We effectively have a 22-player limit now if a team is on a 5-man rotation. And adding pitchers for extra innings really seems like rule complication with no practical difference. We need to change pitcher usage with longer outings to take away some of the advantage of just having a bunch of relievers that can throw 98 for short outings.