A BoP buff would just make it an inferior GT-R clone. Right now it lacks in acceleration, which is easily fixed by BoP, but the main problem it has is chronic tyre wear, which is almost comparable in severity to that of the GT-R, while having nothing to show for it. It handles like a dream, I'll give you that. But even in races without tyre wear, like this week's Race B at Red Bull Ring for example, where even the understeering mess that is the Memesubishi 5 Speed Evo has top 10 time spots in Asia, the Atenza is not even in the conversation.
Besides, if Mazda cars start getting buffs in BoP right after becoming partnered with Gran Turismo, it'd reek of favourtism, and I personally wouldn't want that as a Mazda fan. In the past few BoP changes, the Atenza Gr. 4 has been completely untouched, leading me to believe that PD thinks the Atenza is perfectly balanced
Even with the adjusted tyre wear rates for FFs and AWD, the Gr. 4 Atenza is god awful. I think what it needs more than anything is an adjustible centre diff. The Gr. 3 Atenza is in my mind the best all rounder FR car in Gr. 3 alongside the AMG GT3, and I wholly believe that the sole reason why Mazda hasn't ever made a World Tour event by merit is because the Gr. 4 car is so hopeless. As hyped as I am for the RX-Vision to appear again after 5 years, Mazda right now doesn't need another Gr. 3 car - the Atenza Gr. 3 is perfectly fine. What Mazda needs right now is a firm kick in the balls in Gr. 4.
Or we can skip over all that and "just" get a RX-Vision GT4. Even the Amemiya FD on racing tyres would run circles around the freaking Atenza.