Why wouldn't a therapist do at least some virtual sessions now that they have experience with it and know it's an option?

One of mine (Info) does either depending on the client's needs and/or her own. To her it's a new business model.

The other (Visa) was pretty much a pioneer in the field of online therapy decades ago (probably why she's a lot better at it than your average therapist), though she also does in-person. Successful business model.

And if you mean "only virtual," well, other posters have answered that: health, overhead, convenience, etc.

Nothing says therapy has to be in-person or even that it's better in-person. It's just a new criterion in choosing a therapist. If you want a male therapist, you choose a male therapist. If you want virtual therapy or the option of it, you choose one who does that. I imagine a lot of therapists will continue to offer both and not be exclusively one or the other. I like it.