The scary part is perhaps Bergeron is ready to retire because his passion for winning has passed.
I am the biggest Bergeron fan out there. He is my all-time favourite NHL player (I have his jersey framed in my office, and two Canada jerseys including being the only guy in the arena wearing a #37 in 2010 lol) but if he doesn't want to fight and dig and put it all on the line then that also seeps into the team culture.
In 2011, he was the silent leader with a rookie LW and a retiring HHOF RW. They were the perfect secondary scoring behind a team overflowing with passion, intensity and emotion.
Thornton, Chara, Lucic, Kelly, Campbell, etc. Guys that were so pumped up and feisty that the balance of Bergeron was perfect.
This team on the other hand doesn't have the balance to offset Bergeron's calm and perfect play. They all follow his lead (outside of a quarterly outburst from Marchand).
McAvoy brings some passion but the rest of the list all follow the 'Keep Calm and Bergeron' mantra and have had varying degrees of success under it. Cassidy also follows this (as we see often other coaches calling out refs in the media and emotional outbursts as ploys in a series') but this team seems to be missing the counterbalance of an emotional and intense C.
If Patrice wants to come back and lead this team I expect him to want a guy above him who also brings an emotional level that can balance with him.
JT Miller is too perfect of a fit for me for many reasons but I just don't see the Bruins having the assets to make that trade happen.