Both will continue to go on but the online ones do seem to have increased the crazy spikes in pricing out there. It's like bidding at the last minute on ebay.
What will keep live auctions alive are two things. One the event and entertainment value. Many now are events people plan on going too for a fun weekend. Be it automotive it even tractors.
The other deals is there are people like me that really resist buying a vehicle sight unseen. This often results in major issues or a very unhappy owner. Some cars are well documented many are not. I generally want to look and see just what I am buying.
But online auctions are going to grow as many people in todays market want to buy now not when they find the right car. Some get lucky and get a good car some not do much.
Also if you are selling on line is often cheaper and faster than live auctions if you have a car that is not especially rare.