This pretty much does the opposite. If you don't get a pick unless you are in the bottom, you have incentive to tank...
To me, the better solution entirely is entirely reverse the logic where the teams that have the best records that didn't make the playoffs get the odds in their favor.
1) It doesn't guarantee anything, but gives a tangible reason not to tank (there is no incentive since winning gets you the better odds).
2) As we have seen, if you really want to increase parity, you have to have more good teams. Unless it is a true franchise player (Duncan, Lebron, Shaq, Kobe, Dwight Howard, Nash, Pau Gasol - which is rare), really bad teams like the Bobcats don't become compe ive since it's a gamble and they are usually bad for a reason that goes beyond just talent. However, teams on the cusp of a playoff (like a Golden State, Houston, Dallas, Minny) could really benefit from landing an Anthony Davis type player.
That would help ensure that more teams on the cusp have a legit shot at getting cheap talent enough to make that next level jump and compete for the playoffs.
That's my idea.