I think the only game I've played on my phone that I didn't uninstall within an hour is Sudoku, and that seems like it doesn't really count.
I have a feeling that mobile gaming is at or very near saturation level. That's not to say it is necessarily going to decline, but I simply don't see much room for the industry to grow at this point. People who like playing phone games already play them, and people who don't like them aren't going to convert if they haven't by now. There's not a realistic way to increase their target population like there is with consoles and PC gaming; everyone has a smartphone already, so platform upselling isn't possible. It doesn't help that with the industry boom comes a flood of low-quality shovelware, not dissimilar to that which caused the gaming crash of the 80s. I would not be surprised if people get tired of seeing 100 permutations of the exact same shit, and give up on playing anything that isn't made by Nintendo or at least has enough starting capital to pay people to shill on YouTube.
Personally I would prefer to see games on mobile that just have an upfront cost and no microtransactions. I probably wouldn't play them anyway, but I think it would be better for people overall. Ironically, most mobile gamers would never buy into that because they generally aren't the type of people to buy games in the first place. They have to get addicted first before they start buying crystal or whatever dumb currency their game of choice uses, then most of them end up spending more on the game than they would have if it just cost $9.99 up front. There's a reason all these companies use the same F2P+microtransactions model, it makes them money.