I obviously don't have any insight into your upgrade, but the migration sure seems to take a very, very long time. As you say it's done by the hosting company (Liquid Web, as far as I can tell), I imagine you're using a managed database. In which case it's even more surprising that it takes this long.
However, if you actually do manage your own database, and it's running on a VPS I can give you the recommendation to upgrade the server just before starting the migration and scale it back when it's finished. That's what I do, and it works well for me. (I have a VPS with Digital Ocean.)
Just a thought, hoping it can give some inspiration.