If you prescribe to the idea that the Leafs best chance to win a cup might actually be before the big 3 + Gardiner all have their next contracts kick in (*) then trading those magic beans for a nickel and hoping the prospects provide the same impact during one of the two seasons they have their best shot at it doesn't add up.
I don't think anyone has made the case that you should only trade JVR for prospects or that you shouldn't make any other moves to improve the team immediately while still realizing the rewards of trading your UFA's on expiring deals.
Well, I have.
If, in 2 years, there's going to be a 7-8 player core taking over 50% of the cap, you need to keep finding cheap, talented depth to fill out the roster. Picking 11 times vs. 8 times in upcoming draft improves the team's chances of having depth good enough to contend over the next decade.
I just don't buy that "win now/trade JvR" dichotomy and doubt the team will be significantly hurt moving him out. They'll lose a few goals, probably, but they'll also give up fewer goals.
Keeping him feels like splurging a decent pick on a rental, which is something a team whose window is closing maybe ought to do -- but not the Leafs.