This has been asked a lot of times, unfortunately, that seems a bit far off still. It's likely that the game will in some fashion be supported through to the next console generation, considering transfers to new console servers from PC were available when the console versions of ESO launched. Just gonna have to wait for some sort of official announcement or data mining for anything confirmed, but it's worth noting that the next mainline TES game is still rumoredly 5 or so years off, so ESO support should continue at least until then, which is well into the next console generation.