There's just some things that shouldn't be completely overhauled...and the Original 6 teams fit that to a T.
I doubt the Wings will ever change beyond the winged wheel (fact on that...the logo was based off of a logo used by an amateur team from Montreal that James Norris played for in his younger days...they just modified the wheel to a car wheel in honor of Detroit being the "Motor City"). I think there'd be a spontaneous riot out in front of the Joe if that happened.
Montreal I doubt would
ever change from the traditional CHC and the
bleu, blanc, et rouge...matter of fact, I doubt they'd have signed on with the new uniform system if they had to completely overhaul what they've traditionally worn.
Same goes for the Hawks too...the Indian head is just iconic and I don't see that getting removed/seriously changed around
Rangers too...I think the "Lady Lib" logo is going to get retired and they'll just keep it with what we expect..."RANGERS" down the front diagonally.
The Leafs? I'd be much happier if they brought back the classic, more realistic looking leaf from the 50s & 60s rather than the current one...heck, it might mean they might actually get back to the Finals

(but, on second thought..it IS the Leafs we're talking about (no offense meant to any Leaf fan in the house..all in jest)..)
As for the Bruins...I got a good look at their new threads and the new logos...as a traditionalist, I love them. Love the updated Hub logo and I thought bringing back the very-old school bear was a classic touch. As for the new unis? They're probably the sharpest set I've seen so far.