More like a chance to get a player like Andrew Wiggins. Which, right now, looks more like a nice player to have but not a franchise-changer.
It all depends on what you mean by "tank." Trade away Lillard? Trade McCollum just for draft picks, not a similar talent? Tell the players to play worse?
I've never been a big fan of the traditional concept of tanking--trading away any useful players for draft picks and/or expiring deals. I think you get closer to contention faster by building on what you have than by discarding it all for a "fresh start." If an amazing package of draft picks came along for McCollum, sure, do it. You should always be flexible enough to take advantage of a great opportunity when you can get it. But I wouldn't advocate trading McCollum for draft picks just to do it. I'd prefer to trade him for another young-prime player who may be a bit less good offensively but is much better defensively and work on upgrading the defensive infrastructure around Lillard/New Guy/Harkless.
Last year's second half was a glimpse of what the Blazers could be, in my opinion, with more good defenders. What that team fluked their way towards it's worth actually trying to build for real.