It hasn't been revealed where these new aircraft are going to go, however more information about the proposed expansion of bmibaby should be revealed next week alongside the report for bmi's new business model. We will be able to see the new direction that the airline will be going for. To do a bit of stirring, because we all know that's what PPrune is great at, the rumour has it that at least one of our bases will be transferred back to mainline.
My guess, if this is true, is that Manchester will be the base to go back to bmi. The airline will be able to use the various facilities that bmi has to offer (connections, improved economy service, frequent-flyer programme & business class) to get one up over Jet2, who have been expanding their majorly recently, as well as British Airways CitiExpress who seem to be cutting back in certain markets where they're up against Jet2. Only other base where I could imagine this being useful would be EMA, but this was baby's home base, so not sure if that would be the case ... we'll wait & see!