I mean, why should we hold it against them?
They've done it in the past, and for them to start working on "GT7" only 6 months after GT6 release, there would obviously have to be months of planning before they actually get started.
Even with that said, it is probably likely that this game will last a while, as the DLC alone is going to span over a very long period of time, if we consider the fact that it took 4 years for us to get 170+-cars. What I'm wondering about, is if they're truly trying to reach 500, are we to expect 170 more cars in 4 more years? 330 in 12 years? I'm wondering if they're going to opt into finally outsourcing.