This may have already been noted, but the proposal is for a one-time exception - meaning a player can transfer once without sitting out a year. If the same player wanted to transfer again, then they would have to sit out a year.
As others have noted, pros and cons to this. If you have a guy sitting on the bench who's unhappy about his playing time, it could be addition by subtraction. get rid of a possibly negative influence, and free up a scholarship for (potentially) a better player, or at least a player who's a better fit with the system.
I suspect the vast majority of transfers (if this goes through) would be guys who are riding the pine at a major-conference school, and transfer to a mid-major in search of playing time. I don't see as many "upward" transfers. It would have to be a rare situation - guy putting up big numbers for a bad team, or a team that gets put on probation. In that case, I could see a guy bolting to try and play on a winning team - but that assumes the winning team has an available scholarship.
the scholarship situation will be the big variable. Coaches will have to manage rosters carefully if they lose players to a transfer, or have a space available for someone transferring into the program.