Well, if Ulquiorra
did used to be a Vasto Lorde, then chances are that the top three Espada, being more powerful than him, were Vasto Lordes too. Now, considering that just ten Vasto Lordes would apparently be enough to defeat all of Soul Society, I'd say the captains & lieutenants need all the help they can get. This leads me to believe that not only will the Vizard get involved, but so will Kisuke, Yoruichi, Tessai and (possibly) Ichigo & Uryu's dads.
Why did the old captains even become Vizards? >_>
I'm up to date on the manga and I don't understand how thats happened.
Are you sure you're up to date?
SpoilersRight now, in the flashback, all the captains & lieutenants that become Vizards are currently incapacitated with Hollow masks forming on their faces. It hasn't explained what caused it yet, but it explains how they became Vizard.