You can't determine a baseline based on a single week of sales.

Baseline last year varied a lot due to exceptional circumstances (COVID measures). You could put it anywhere between 3,000 to 7,000 units.

Even if Switch recorded another week between 3,000 to 4,000 units next week, it wouldn't mean much because a series of noteworthy game releases is coming up, starting with Super Mario 3D World + Bowser's Fury on February 12th. Afterwards, there's Bravely Default II, Monster Hunter Rise and New Pokémon Snap, so the February to April stretch is an upgrade over the nothing of January.

If Switch sales remained in the range of 3,000 of 4,000 during that time, then sure, that would be a baseline. But I don't think that's likely and instead we'll see fluctuations for a while. There's a Nintendo Direct scheduled for tomorrow, so the remaining mysteries of Switch's first half 2021 schedule will be solved. New Pokémon Snap in April is really how far public knowledge stretches at this point and that's only two months in the future.