Xbox launch line-up seems just fine to me, I know I plan to play several of those games. And the 2021 line-up also looks fine, with games like Flight Sim, Halo, and almost certainly Forza Horizon 5. Scorn and Second Extinction have a good chance of a 2021 release. Exomecha, Call of the Sea, Bright Memory Infinite, and Hello Neighbor 2 are already confirmed for 2021. 

a. As far as we currently know, Sony only has 3-4 big exclusives for 2021, Horizon: Forbidden West, Ghostwire Tokyo, Deathloop and Demon's Souls remake (assuming it isn't a 2020 game). Xbox will have 3 big games for 2021 most likely, Halo, Flight Sim, and Forza Horizon 5, possibly more since they still have a 3rd 2020 show and E3 2021 where they can still announce more 2021 games. 

b. As far as I know the only games on my 2021 list that are already released on PC are Flight Sim and Bright Memory. Bright Memory is in the 500k-1m range on Steam Spy, which isn't bad at all for a game developed by 1 person. Flight Sim just released and according to an insider is selling on pace to sell more than 1m in the first month.

With no Halo, these are very much just run-of-the-mill launch lineups. The most interesting part will be the price discrepancy between the multiple skus, and the difference in performance of multi-plats.

Just patiently waiting for next E3. They'll both sell well out the gate regardless, but I don't expect much excitement from next-gen before then.

a. I'm not a fanboy of any system, I'm a multiplat gamer as you can clearly tell from my signature which shows my Xbox achievements and Playstation trophies.

b. Forza Horizon 5 is not made up, it is known to be in development and almost certainly targeting a 2021 release for several reasons. Forza Motorsport reboot is rumored for a 2022 release, and since MS won't release both Motorsport and Horizon on the same year, it's a safe bet that Horizon 5 will release in 2021 or 2023, and of those two windows, 2021 is far more likely; if they wait until 2023 to release Horizon 5 then they will have no Horizon game on the store by late 2022, because Horizon 4 ill be removed in September 2022 as MS only pays for 4 year licensing deals for cars and music for the Horizon games. 2021 would give it 3 years of development, 1 year more than any previous Horizon game. Also, Playground racing team has been doing massive amount of hiring since Horizon 4 released, they've gone from about 110 devs when Horizon 4 released to about 160 now, and still have 36 open job listings for the racing team. The huge uptick in recent hiring especially indicates that the game is entering the final stretch of development and they are bringing on more people to help get the game home.

c. We were specifically talking about big games, AAA games. The only big games that Sony has announced with a 2021 window are Horizon: Forbidden West, Deathloop, and Ghostwire Tokyo. Demon's Souls remake has no date or window, but based on the recent ratings in Korea and Japan, is most likely releasing in either late 2020 or early 2021. Ratchet and Clank was announced with no date or window, it may release in 2021 but that is far from certain with Sony, in the past they have often announced games that are more than a year away from release, and announcing without a date or window is often a good indication of that. Those are the only AAA exclusives that Sony announced that might make 2021 at all. Project Athia is known to be early development, it doesn't even have a proper title yet, might not even release in 2022. Returnal is developed by Housemarque, a AA studio. Stray, Volcano High, and Solar Ash are 2021 but they are all indie/single A games.