I feels like the Pens are in a bit of a Catch-22,:
If you try to tear it down now, it's just too soon. Sid and Geno are no longer in their prime, but they're still elite players. Their pride will drag the Pens at least to bubble status, if not into the playoffs, for a while to come. So you end up not quite being bad enough to get the high-end draft picks, but you're also not quite good enough any more to win the Cup, or maybe even make the playoffs, as you've unloaded the supporting cast, and simply hoping that the prospects can be good enough (most won't be, statistically speaking). Then you've stockpiled prospects who aren't the top-end ones, and they all become NHL ready, just in time for Sid and Geno to retire. So now you no longer have the vets to trade for more picks and you're bad, because you just don't have enough high-end talent. So you have to go through another rebuild, when you just went through one (See: Oilers, Sabres).
If you don't tear it down now, and just keep going for it, you risk simply dragging out a period of mediocrity: trading assets to try to improve enough to maybe be good enough to make the playoffs, but not good enough to win the Cup. On the flip-side, this sets them up better for when Sid and Geno are at the end of their careers, and it really is time to rebuild in earnest. Sell off the vets at that time, get some high draft picks, and maybe have those prospects overlap with Sid and/or Geno for a year to two.
Then there's the option they're going with now: re-tool on the fly. Trade older players who aren't working out for whatever reason for younger players who aren't working out for their current team, but might for the Pens. There's plenty of risk. This could just as easily end up with a dragged-out period of mediocrity as well. But it at least has a better chance of catching lightning in a bottle. Plus, you can still fall back on the "rebuild at the end of Sid and Geno's careers" path.
I know some people are hoping for a scenario where the Pens bring in enough young guys that once Sid and Geno retire, the young players can pick up the slack and continue to carry the team forward to the playoffs and more Cups. The Red Wings thought they could do that post-Lidstrom, and well, it hasn't been pretty. I just don't see a realistic path for the Pens that goes down that route. There's no equivalent to being the only team scouting most of Europe and drafting late-round gems like the Red Wings did when they landed Datsyuk, Zetterberg and Franzen any more (especially since you can't even draft 25 year olds anymore, like the Red Wings did when they drafted Franzen...).
The only likely way to really get to a "draft high sooner rather than later" would be to not have Sid and Geno. I'd rather still get to watch them play for a bit longer, myself....