This means that a priest can make the intention once, to "do as the Church does for the rest of my priesthood," and that suffices for intention for the rest of his priesthood.
That is, in fact, what most priests do.
But what if he changes his mind and no longer wishes to do this? What if he becomes an apostate or heretic somewhere down the line?
I'm not certain that "once-and-done" is a valid interpretation of "virtual;" but certainly a priest who prepares himself for Mass and who even momentarily THINKS about what's about to transpire would have 'virtual' intent.
One would think that such thinking/preparation is almost automatic, although I would strongly urge priests to make it a point to stop just before entering the sanctuary to renew 'intention.'