I think Biden will end up proving to be the converse of Trump: that is, just as Trump's ratings remained consistently stable with an approval rating in the low-to-mid 40s & a disapproval rating in the low-to-mid 50s, Biden's will also remain consistently stable, but with an approval rating in the low-to-mid 50s & a disapproval rating in the low-to-mid 40s. In fact, the (admittedly little) polling which we've already gotten on Biden's approval rating thus far is already ~10 points better than where Trump was 9 days into his presidency (which makes sense, given that he's obviously considerably less polarizing than Trump), so to some extent, this effect could very well already be showing up before our very eyes, though we'll obviously need months' more of approval polling to confirm whether or not this apparent trend might be sustainable.
At the very least, if - as is expected - the economy is well on its way to being (if not already) back & booming & life is well on its way to being (if not already) back to normal a year from now, then I see no reason to expect his having a consistent approval rating in the low-to-mid 40s at that time (other than SN's hackery perpetually clouding his judgment, of course).
While I don't think it's fair to assume that Biden's approval ratings will be the inverse of Trump's (due to the left's propensity to eat their own), the rollout of the Covid vaccine and the economic recovery will probably help Biden stay afloat.