Easy there, fella. This is being dangled now by the dems to try and stem the flow of supporters leaving leading up to election season. If things look good for them leading up to the election, you won't see this big move happen. But if whoever they trot out there isn't doing well, they'll drop the decriminalize bomb in a last ditch hailmary effort.
It is funny that this hasn't already happened, tho. If any sitting president would have done this, they would have garnered instant overnight support from a very large segment of people. Not the diehards for the opposing party, sure. But the undecided and the don'tgiveafucks would have been swayed. And the supporters would far outnumber those opposed, imo.