I think what is gonna be interesting is the legs for Arceuas moving forward. Historically, mainline Pokemon games usually have shorter legs due to the next game being announced. However, it seems that Let’s Go and Sw/Sh have managed well. Granted, Sw/Sh had a little more than 2 years to breathe before BDSP and had an Expansion Pass. BDSP doesn’t seem too bothered by Arceus’ release as BD is still on the eshop best selling titles chart.
the tough part about Arceus will be keeping players engaged post game, there’s not much to come back to apparently once the Pokédex is completed even with the upcoming update. Will be interested to see if they’ll add more after. Competitors play Sw/Sh for online competition. Arceus isn’t meant for that, especially with its unique battle system.