It's not a new tactic, some Sevens teams have been doing it for the better part of a decade, and the Chris were doing it quite a bit a couple of years ago. Still, Brilliant stuff by Italy, albeit it isn't what you want to see every time two mismatched sides come up against each other a lá the park the bus in football.
I think you won't see any rule changes or anything, but before the June Internationals, there will be a comprehensive series of interpretations released based around whether or not pulling players in counts as a ruck, how close a player can be to the halfback etc.
As has been said, it's not a winning tactic in and of itself, it took a "favourable" interpretation by Poite, and England being unwilling to think outside the box in the first 33 minutes. For example, none of this standard pick and go, or one pass stuff, have Teo, Hughes, Itoje or Nowell run straight fucking over the top and look to offload with all the close defenders behind you.
At about the 36th minute, Danny Care has a snipe when no one commits to the ruck then chips and chases, nearly getting a try. They didn't do enough of that.