I think it does matter, but not for this year. I'd agree with the general proposition that there isn't a team in the West that will beat LA, absent a rash of key injuries in Los Angeles. They're too long and athletic for everyone and when all else fails, they have Kobe's big-game ego to fall back upon.
Where I think the course of this series does matter is in deciding how to proceed from here. Maybe a continued struggle to find scoring from sources beyond the Big 3 convinces Spurs management that it's time to recrack the window on the Duncan era by finally committing to youth (ala the summer of 2002). Maybe it convinces them to find whatever way possible to get Tiago Splitter here -- or to get something truly useful from his rights. Maybe it convinces the Spurs to pony up the $3 million it might take to buy someone's #1 pick and infuse youth that way.
Whatever the path, getting bounced early (all relative, I guess -- so many teams would love to be facing the possibility of not winning a series for the first time in nearly a decade) might be the impetus that the Spurs need to make changes; winning the series and advancing a couple of rounds might be worse for the Spurs by suggesting (erroneously) that a healthy Manu is all that separates the Spurs from a real shot at another le.
Props to the Mavs for playing harder and better through 4 games than the Spurs have.