Would be interesting, but afaik impossible in vb, let alone vb3.8.
My site has something a bit like what you're saying, it syncs all the connected clients and you can see other people typing in real time.
example.
But yeah, that's written in Go, where as these forums use php. I'm sure there could be improvements made to the notifications using AJAX though.
In anycase, the overhead for this would kill tb's bandwidth! Would be easier to add @User mentions.