The bottom line: Will Beckham make a long term difference?
IMO, No.
Now that's just a guess of course, but there are some factors to consider.
1: There is an ever increasing number of people immigrating to the USA who enjoy soccer immensely.
and
2. There seems to be an increasing amount of kids in Americas schools who are playing soccer more than ever b4.
So anyway, ready or not, here he comes.