To the question of evolution (no, not that question), I love to speculate as much as the next guy.  But you're absolutely right about this situation, and it makes it almost impossible.  

Livingston - do we get to see him 25 games this season?  Or zero?  Likely somewhere in between.  How does he look when we see him?  Best case scenario - we see him and he looks like he'll be the starting point guard for years and years (he's only 22 remember).  Worst case scenario - we see him and he looks bad and tentative.  Of course, not seeing him is almost as bad as the worst case.  But given the importance of the position, and the Clippers situation beyond Livingston, it is a distinct possibility that point guard will be the top priority in this draft.  But we don't know that.

Draft position - Dropping lower than 6 seems unlikely.  Sure, the Wolves and Sonics have played a little better.  Even the Knicks I guess.  (Based on recent events, it seems to be a two team race between Miami and Memphis for the worst record, but you have to put your money on Memphis.)  But none of the teams below the Clippers in the standings are expecting to add a multi-time all star to their roster in the next few weeks (as far as I know).  Don't look now, but we've already passed Charlotte in winning percentage; Milwaukee is next, and 5 other Eastern Conference teams are within reach of an EB fueled LAC run (maybe even Sacramento).  One huge advantage for the Clippers here - the bottom of the East is so bad, that all of these teams also have a legitimate shot at the playoffs.  A tank decision for any team currently better than the Clippers has to come at the expense of the playoffs.  There are currently no teams who can say, 'We're already out of it so let's improve our draft position.'  A modest win streak and you're in the playoffs (look at Philly).

Finally, don't forget that the draft prospects themselves are moving.  I don't know anything, but the people who do know are going to have these guys going up and down the charts.  Someone we've never heard of could suddenly be in the lottery based on a late surge and draft camp athleticism off the charts.  

Shooting guard (and shooting) will be a need of the team, that much we know.  Point guard may or may not be a more pressing need.  

Of course the problem is that we're talking about the 4th pick in a less than amazing draft, and certainly not the point guard bonanza that came up the next season with Paul and Deron Williams.  Devin Harris was picked 5, and the Mavs are packaging him to acquire Jason Kidd - something the Clippers chose not to do last season with Livingston when Kidd was a year younger.  Of course that was pre-knee-injury Shaun, but we've already said the injury thing is the unknown here.  Or did you want Sebastian Telfair from that draft?

Do I hitch my wagon to Livingston at the point?  The simple fact is that you can't wave a wand and get everything you want.  With one first round pick, you get one player.  I think finding shooting (in Mobley's replacement at the 2) is the higher priority - if Jerryd Bayless can realistically be that AND a point guard option, then that's just dreamy.  But I think the 'home run' approach here is to assume Livingston is the starter at the point and work on other issues.  And it goes without saying that the final two months of the season will add more information to this discussion.

The guy is 22.  Look up the early NBA careers of Chauncey Billups and Steve Nash.  Nash became the full time starter in Dallas in his fifth season at the age of 26.  Billups was on his 5th team, in his 6th season, and also 26 before he was a full time starter.  It's WAY too early to give up on Livingston.  Sign him to the qualifying offer and get another year of data.  (If he'd be willing to take more years for less money, I'd do that.  Something like 3 years/$10M.)