Unless it comes with a Bluetooth controller and somehow works without appreciable input lag, no sale. A touchscreen alone is just not an adequate gaming input device for any but very simple games. That's why Nintendo still makes consoles.

The main problem with IAPs is when it becomes pay-to-win, whereas a free game with aesthetic IAPs is better appreciated. For example, DotA2 has worked for Valve (though it has an extremely toxic community and way too many scammers, but that seems easier to manage on mobile).