It makes it nearly impossible for you to be able to sign a full compliment of 25 players unless you luck into a situation where your all of your recruits are willing to officially make a decision well before signing day.
Every year, almost every school has at least 4 or 5 players at a minimum that are making signing day decisions. I remember some years where we had as many as 10 or 15 players we were still recruiting who hadn't made an official decision until either signing day or the day or two before signing day.
Even without the 25 rule, we had years where we nearly struck out on all of those remaining players and ended up with a well-undersigned class, and we had years where we cleaned up on those final players and ended up well-oversigned for the class.
The only solution I can think of is that teams are going to have to leave a lot of spots open and take a big risk of undersigning every year, or they're going to have to go ahead and fill up their spots and have to turn guys away that want to make signing day decisions.
The only other option, and I see this happening, is that we'll see players be asked to not sign on signing day. Where you might normally sign 28-30, before the completely asinine rules were put in place, planning on 3-5 of them not making it to campus and/or one or two of them grayshirting, you'll see only 25 signed, and 3-5 players will be asked to just not sign with anyone and plan on coming if a spot opens up or grayshirting if a spot doesn't open up.
If you're Florida and you have the luxury of cherry-picking somewhat and knowing you don't have to sign academic risks and you can force players to make early decisions, you don't have to worry about this rule. For the majority of the SEC, these signing rules are awful.