As things currently stand they very much need VV. There is no guarantee that both Moore and Anderson will pan out, and Howard either seems ticketed for AAA or won't be available to pitch by August (though those things also seem in opposition to each other, and by August they could also have acquired a new pitcher).
But if you actually signed Odorizzi he's quite possibly your #3 starter, and certainly your #4, even if his 2020 was a mess (which is also why he ought to be available more cheaply at this point). At that point they'd not only need to trim a little payroll but couldn't carry all those rotation arms - If the lefty Moore is your #5 and Howard is in AAA one of Anderson or Velasquez would become a swingman/long reliever/6th starter, but you don't need a $4 million 8th starter.
The other idea, of course is that VV might become a higher leverage reliever, but we've never been able to find out, and if Watson and Kintzler both look good in camp I'd sooner bet that money on them.