It won't. Again, Polyphony isn't that stupid. If they did, it'd be offered for trial use like every one of the few one make, one car Sport races they've done with a car worth more then a million credits.
Again, Polyphony isn't that stupid. They'd know that'd tank their game hard if that was the case.
Here's the thing: it could. It's not going to happen, though, because A: Polyphony isn't that stupid or bull-headed (anymore) and are cognizant of the player base and their expectations after two years of free updates. And maybe most importantly, B: Being a wholly first party developer under Sony means that they can eat the cost of making most of the post launch content free and have it not matter considering GT's position as a system seller.
That's not what's happening, nor does it look like it's happening considering what this paid DLC is, Polyphony's moves going back to the very launch of this game, and who they're owned by.