I provide online training, video training and live training on Power BI, Excel Data Analytics etc.
I think that what we refer to as Virtual Training (which is where a trainer teaches a small class using Zoom or Teams) is highly effective. In our case, we keep classes small (max 6),which means everyone gets personal attention, people tend to feel comfortable to ask questions, and the course tends to progress more quickly because everyone stays focussed and I don't have to walk from desk to desk answering the same question 4 times (I answer it once and everyone watches so they all get the question answered).
Online video training (where a learner learns by watching a video) efficacy depends very much on the individual's motivation. For those who are motivated and willing to sit through the training, I think it can be very effective. However, the problem is that so many people sign up with intentions to do the training and unless there is some kind of deadline, it's so easy to just postpone the training for day after day until you realise it's been months since you signed up to do the course! This is where an actual dedicated course where the time is booked out is often more effective, albeit more expensive.
But I do think the frequency of live, face to face courses will diminish. I can deliver training that is probably as good (if not better) remotely, my costs and time commitment are way less which means I can charge the customer less, and learners get many of the benefits of live training. So yes, I think virtual training is going to take over from live training for applicable courses to a large degree. Video courses will remain popular due to their low cost, but as to how effective they are, that's not so clear cut.