I'm wondering the same thing as you. However, if done properly this could look pretty realistic. For some reason I think there will definitely be problems. How it could work though is based on speed. Harder hits result from guys going into hits at top speed. Low speeds might result in just a bump, which is exactly what we would want to see. With the current button system, you can flick the RS and have a chance at demolishing a guy without having any weight or speed going into the guy.
As for goalies, did you play NHL 12 at all? In NHL 12 they had goalie collisions. In fact the back of the box and big feature for the game was "For the first time in this series goalies are now in play." The funniest part of this is that it was non existent in NHL 13. So they hype it up as a feature for 12 and then take it out of 13 for absolutely no reason. Now they are showing goalie collisions off in their trailers for the new physics system, to sell the game again hahaha.
Anyway, the goalie collisions didn't work too bad in NHL 12. Sure the physics of it weren't all that good, but how it worked was pretty decent. You actually had to be aware that if you were crashing the net you better slow down to avoid interference. It wasn't as if guys were just flying into the goalies all the time either. I mainly would just crash into the goalies on purpose when I was fed up with the AI and repetitive CPU. It helped me get rid of my frustration quite well.
Edit:
Onac I now see that the blog is up for it. It appears they have reworked the penalties to fit in with the new system. As I had thought it is all based on LS hitting (so running into the player) but you can still use the RS for hitting to, I guess.