Bee, to the extent the new deadline forces earlier decisions, that can work to the benefit of the player. However, if the player isn't signed and goes to a 4 year school, he isn't eligible to be drafted until age 21 or after his junior year.
The team that did not sign him gets to repeat that pick in next draft plus their regular pick for that draft. Just my view, but, on its face, I think this gives the team a bit more leverage than it does the player. In the past the team would waste the pick if the player did not sign. Now, the team gets additional picks the following year for players not signed.
In general, I think we are talking about a very small percentage of players. The number who signed out of high school and decided they hated it and wanted to "void" the contract does not seem to be many. The number who don't sign and end up "unhappily" in college does not seem to be many.
This may change some with the removal of the draft/follow for the JC option. I do think this thread shows how complicated things can be and why every player who has these types of options out of high school can use the benefit of very good and comprehensive information or an extremely good advisor.