First off, no. It has been said before and I reassert SEGA is not trying to ruin nor destroy the Sonic Franchise. Many have said already that doing so is counterproductive due to great amounts of money lose and time that they could've spent trying other things. Take Capcom and Megaman for example, you can tell that a couple of years ago they were trying their hardest to make a good Megaman game that was new, fresh, innovative which resulted in games such as Megaman Legends, the ZX series, etc. And what happened after that? Project, after project Capcom attempted to bring back Megaman to the scene, except for the fact that all of those projects were cancelled, until the point they just didn't announce any other Megaman games.
Now, what does that have to do with Sonic? Well if Capcom gave up on Megaman, or at least, it seems to be the case, why would SEGA instead of dropping the Sonic franchise completely try to make games for the sake of destroying it? It just doesn't make sense, it's not logical and far more expensive costs come along those attempts. SEGA is trying their hardest to craft a good Sonic game, and to be honest, I agree with what Superiorstar said, they don't listen to their public audiences. Debate after debate, review after review on YouTube, their voices are there but SEGA just doesn't listen to them.
I can safely say what SEGA tried to do for Sonic on Unleashed got them on track, regular Sonic gameplay seemed to fit way better than anything they've tried before. It just needed a couple of tweaks and it could've been perfect and SEGa knew that. Proof of that is that the next games to be released after Sonic Unleashed were none other than Colors, Generations, and Lost World, considered by many to be the gems of the 3D era of Sonic (What? There was a Sonic and The Black Knight in there? Shut up I don't acknowledge that game). I'm not a fan of Lost World myself but compared to the rest of the Sonic games I can safely affirm that it didn't fall that back.
So no, SEGA hasn't given up yet. All we can do is wait patiently for a good Sonic game ... and pray, but why would you do that?