I agree, they will likely get an exception as there was no opportunity for them to play, and the ITF is very lenient. I mean Wozniacki has played for her country once since 2011 and still got to play Rio and I'm sure they would've let her play Tokyo if she didn't retire before.
I am more interested to see what happens with the Grand Slam/legacy wildcard spots. I'm sure it won't matter for Venus Williams as she won't be in the top 4 Americans. Andreescu can use a protected ranking to get automatic entry to the Olympics. And I don't think Muguruza will be back before then (if ever).
That leaves us with Wozniacki, Kerber, Halep, Osaka, and Raducanu. I don't think I'm missing anyone else? There are only two spots.
Time is running out for these girls to get in directly, so in the end 3 of them could miss out...