From various smaller pieces of evidence, we can conclude that the blinded condition of wall of light can last past the spell's duration
Spell effects can last past their spell's duration
The clearest example of this is the haste spell, which states:
[...] When the spell ends, the target can't move or take actions until after its next turn, as a wave of lethargy sweeps over it. [...]
This is an extremely explicit instance of a spell having an effect after the spell ends. But we do have other examples of this, like numerous spells with a duration on Instantaneous, let's look at the example of the [pyrotechnics]pyrotechnics spell:
[...] The smoke persists for 1 minute or until a strong wind disperses it. [...]
Note that this spell has a duration of instantaneous and yet it has an effect that lasts for an entire minute.
Conditions end only when they say they end
This is almost literally just a reiteration of the "Conditions" section of the rules:
[...] A condition lasts either until it is countered (the prone condition is countered by standing up, for example) or for a duration specified by the effect that imposed the condition. [...]
This is more just to show that the condition would not simply end because the spell ended; and in fact...
If something ends when the spell ends, it states as much
An example of this is the charm person spell, which states:
[...] If it fails the saving throw, it is charmed by you until the spell ends or until you or your companions do anything harmful to it. [...]
This spell explicitly states that the charm effect ends when the spell ends. And from these pieces of evidence we can conclude the following:
The blinded effect of the wall of light spell can exceed the duration of the spell, the condition does not end simply because the spell ends (no general rule makes this the case), and the spell states precisely when the condition does end which is once 1 minute has passed. It does not give any other methods of ending the effect, so there are no other methods of ending the effect. Except, of course, for methods that explicitly end the blinded condition (like lesser restoration) or methods that cancel spell effects (like dispel magic..... maybe).