I wanted an M&P10mm in the worst way for the longest time, but ultimately gave up on it and due to shortages ended up going in a completely different direction, and got myself a Heckler & Koch USP45 Elite earlier this year along with a few boxes of Buffalo Bore .45 Super ammo, which satisfied my need for a powerful semiautomatic pistol quite nicely.
I still wish that Smith & Wesson would come out with an M&P10mm though, if only for the folks who really want one and haven't selected a suitable alternative yet.
I may be being pessimistic here, but I really don't think it's happening, and a piece of cardboard with the M&P Logo and 10mm printed on it isn't nearly enough to convince me otherwise. So until Smith & Wesson announces it themselves, it's a hoax as far as I'm concerned.
For those of you who may be convinced that an M&P10mm is inbound based on that picture, then hold onto your hat for this one...
10mm Auto? Pfft... Try 20mm Vulcan!
Seeing is believing, right? And I just provided a much more realistic image than a simple piece of cardboard! Believe it!
But seriously, temper your expectations and await official confirmation before you get all excited over the M&P10mm or even the M&P20 that I just showed you and therefore it definitely exists.