I would bet it being like CSGO to CS2 or the DOTA 2 Source 2 update. Better to keep your player base in the same game through a major update rather than split the fanbase between games like how the counter strike community split between CS1.6 and Source for a good decade until mostly converging into CSGO
So players have to re-buy all the champions and skins that they already bought. Dats smoit.
I would bet it being like CSGO to CS2 or the DOTA 2 Source 2 update. Better to keep your player base in the same game through a major update rather than split the fanbase between games like how the counter strike community split between CS1.6 and Source for a good decade until mostly converging into CSGO