Disagree with this. In a 4-2-3-1 I think you're spot on that a Herrera/Vidal/Mata midifield lacks balance and places too much of a holding requirement on Vidal, when you really want him pushing up and effecting the game high up the pitch - both with and without the ball, the latter allowing him to press high up and win possession.
In a 3-5-2 I don't see this as an issue however, with the security of three centre backs there isn't the same requirement for a DM. They offer more focus and ability defensively than a holding midfielder, so the difference someone like De Jong would make would be negligible if he replaced someone like Jones IMO.
In fact, with Herrera and Vidal I actually think an extra centre back compliments that duo better defensively than another pressing midfielder - Vidal and Herrera press already and Vidal in particular is one of the best ballwinners playing right now. An extra defender to be responsible positionally is more of a requirement than another midfielder in there.
Vidal/Herrera/Mata in a 3-5-2 is a great fit IMO and much better than a 4-2-3-1. I agree that there will be a far greater requirement on Vidal to hold than he had at Chile for instance where he played off the forwards, and to a lesser extent a bigger defensive role than he had at Juventus. But the difference is not going to be huge in this system and IMO Vidal could pretty much still play his natural game.