Wait a minute, wasn't everyone complaining about the course maker being a mobile app? And now one of the reasons that GT could end after GT7 is mobile games? That also need a compatible mobile device (tablet, smartphone), just like the course maker does? How the hell is mobile gaming taking over console gaming?
Tablet/mobile version of GT7?? Do you even... brain? Oh, I get it, let's carry a wheel everywhere with our tablet to play Gran Turismo... Or a DS4 controller... Or use the touch pad, which is very good to play games... Whats's next? We already have gaming PC's, sometime we will get be getting "gaming Smartphones"? That's a nice excuse to make those already overpriced smartphones (that last what? One year for most people?), even more overpriced... And the battery with the modern phones drains very fast, now imagine in those "super advanced gaming smartphones"... 5 minutes of battery...
The main reasons for the lack of sales, was the game being released pretty much at the same time as the new consoles and games such as GTA V, BF4 and a bunch others, European crysis, etc. Really bad timing. The audience is also changing a lot, the marked as changed, and that you can see with every other game... This generation of gamers is obsessed with looks, just watch the first trailer for fallout 4, and the reactions to it... "oh the graphics suck", "It looks just like fallout 3". This is just an example of what this generation of gamers is... you either have some solid fanbase that will buy the game no matter what (COD or FIFA), or you have to do a lot more to keep the sales up. In a game like Gran Turismo, you really have to love cars in some way to buy it, and that audience is vanishing. And it's not the gaming industry that is getting messed up, the music industry and the clothing industry too... No matter how good is your music, or how well made some clothing brand does their products, what's mainstream will always sell more, that simple. Sad, but it is what it is... All this just to say that, the game has to improve, and will improve somehow and in some way, but will never be perfect and will never hit sales numbers as before.