Russians for example have embassies in Europe with staff count that clearly isn't required for normal operations and everyone knows that they are spies. I suppose it's easier to keep an eye on them when they are close by. On the other hand, nothing important would be lost if we just kicked them out.

They also do do normal diplomacy to some degree too, which is basically the obvious part of advancing one's interests - but a lot of stuff is definitely going to be easier to work out face to face.

There is also the problem of technical difficulties.

Setting up secure, verifiable communication channel that is available regardless of disaster or other difficulties would be hard.

I understand most people are used to Zoom and equivalents, but observing is different from making decisions at the highest level. I also think that some of the communication is of the kind that you would want to be sure cannot be recorded.

Would be a shame if everyone sent them all home?

With global covid it will only be responsible to do so... lol...

Never gonna happen though

Exactly. Worldwide closure of embassies. Online services - visas etc. Might have the in-person admin work outsourced to 3rd party international corporation.