No, the glue of that line is that they're all 6'1+, can skate like the wind and forecheck hard. That's all that line does. I don't think it's going to produce particularly well at all. Sure Hyman picked up a couple goals but we all know Hyman well enough to agree his main contribution isn't his production. The utility of that line is that they can run people over, overwhelm and harass the defense, and keep the puck away from our net while we wait to put the top 2 lines back on the ice, which is honestly a very useful thing. You put a 36yo Eric Staal in the middle of that line instead and it's not obvious to me that it'll be a proportional, one-to-one upgrade. It changes the identity of that line. For better? For worse? I don't think it's obvious.
I'm not against acquiring Staal, certainly guys with experience playing both center and wing are the best depth players to have, but I don't think line building is simple arithmetic. I'm not sure he actually makes the 3rd line better, I'm not sure we can expect him to keep up at the center ice position, and I'm not sure making the 2nd line even slower by sticking him next to JT is a good idea.