I have often wondered why a city as large as San Diego never had a GW store. Not that we needed one. But alas GW is staking their claim in April.
We have 6 LGS spread out over 20 miles that have gaming rooms/tables for 40k (and other games). 4 of them have a dedicated weekly 40k night/league.
Even with the GW store opening just a few miles from a LGS I don't think they will effect our stores much at all. If anything they will help!
We are a Military town. 3+ Navy bases and 3 Marine Corps bases (including 1 of the 2 boot camps). Every game store offers a 10% military discount. I doubt the GW store will.
I think the GW store will introduce young people to the hobby, and they will then migrate to the other stores to play.
But this is all just my speculation.
What experience/observations do you have when a GW store opens near other Local Game Shops?