There isn't a right answer here, just a philosophy, really (go for it or don't sell the farm). This is my philosophy...
We saw in the 90s how difficult it is to win a cup, despite a sick roster of talent. I still can't fathom how the Isles beat the Pens in '93, but it happened. The next season Mario barely played and Stevens broke his face and was never the same again (then got dealt to Boston shortly after). Tocchet was also traded shortly after that.
It happened that quickly and before you knew it, the Pens mini dynasty was over. They never played in another SC ever again, despite still having players like Jagr, Francis, etc.
We saw how quickly Crosby can be taken away with his concussion issues. A career ending injury could take him or Malkin away from this team before their time. Letang may get traded, etc. These guys may stay healthy for another ten years, but never sniff another cup.
I learned that harsh lesson over a decade ago.
Nothing is guaranteed. That's why when you have your team healthy and playing well, with a weaker than usual East, you HAVE to go for it.
Shero doesn't have to sell the farm, but he needs to fortify this roster and give them help. If he sits on his hands this deadline, I won't defend him when others blast him, that's one thing I feel quite sure about.
He has to seize this opportunity. It's what top notch GMs do.