This new method is something they discovered in their journey to emulate OG Xbox games. Unfortunately aside from a few paragraphs I've not a clue how it works. The Heutchy method? perhaps I have his name wrong. But basically intercepting the emulation process and making swaps without the game code knowing.I wonder if any of the OG titles that included some form of AA (Shenmue2, Bloodwake, PGR2, perhaps a couple more) will ever hit XBO/XBX backwards compatibility. And, if so, if there will be any visual irregularities from re-rendering those games at much higher resolutions. Rights shouldn't be an issue with Shenmue 2. Microsoft published the game and they already had BC rights once on the 360. That emulated version stunk, though. Missing AA and broken features. I think AA was also turned off in the 360 emulation of PGR2.
Is there any reason to think that Original Xbox antialiasing functionality is incompatible with whatever Microsoft is doing to render these games at higher resolutions on XBO?
Not sure, I do recall that they said it wasn't applicable everywhere (referring to OG Xbox titles), but I'm not entirely sure where it's applicable on 360 titles either.
With directx and drivers you can probably override some things, for instance you can use the Heutchy method to replace some art with higher resolution versions of it, but I'm not sure to the extent that you can fix broken features.