Re: Microsoft Stores execs must be worried then ;-)
I passed the first Microsoft Store I've seen, in New York's Times Square, just the other day. I can't talk to sales totals but it was definitely packed. That said, I'd imagine it's difficult for anything next to Times Square not to be packed.
If Apple's Stores stopped selling anything? I don't think Apple would do anything because I think that'd be symptomatic of the end of Apple. The post-2000 Apple as a purely consumer company lives and dies on its ability to attract lifestyle purchasers. I'm not sure they'd be able to contract back to the design and technology-obsessed* niches they held last time things went bad.
(*) in that the PowerPC really was quite a bit faster than the Pentium for a long period in the late 90s and RISC snobbishness shouldn't be underestimated, and nowadays there's the 'it's also a fully certified UNIX' angle plus things like the retina display.