Yes, there are some other slim (and not-so-slim) single stack 9's on the market.
If S&W is able to get this new one to run as reliably as their previous 3913 & CS9, they've got a winner on their hands.
If the grip is thinner than the CS9, they've got a winner on their hands.
Even if it only has a magazine capacity of 7-8 rounds, they've got a winner on their hands. (Will it come with a short/flush & extended mag?)
If it has the new pending M&P trigger improvement, they've got a winner on their hands.
If it's simpler in design than the PPS (from an armorer perspective), it'll sell well to LE who have agency armorers.
Some folks seem to like a thumb safety on their M&P (I've got 1 with the TS & 1 without), and a reduced size lever would probably be welcome by most owners who aren't wedded to the 1911-style safety lock lever. (I only got mine because I'm a long time 1911 owner/shooter and I wanted to try one.)
If they have a .45 model in the wings ... to replace the CS45 subcompact ... they'll have orders back-logged for months.
Personally, I'd try one in 9mm ... after it's been on the market for a bit. I dislike Kahr triggers and I was rather unimpressed with the LC9 I recently tried. Its grip and trigger would have prevented me from wanting to buy one ... even if the gun hadn't exhibited frequent light-strikes with an assortment of ammunition. (The owner of that particular LC9 got rid of it after it had been repaired by Ruger, but the light-strikes continued with 124gr +P duty ammo.)
Yep, there's definitely room in the market for another slim single stack 9.
I'm not getting rid of my 5 other small 9's, though.