Re: will dawn and brock come back
Since Misty and May made an appearance after the season they've been on the journey with Ash (for example, May appearing in Sinnoh and Misty appearing in Hoenn), I think same thing's going to be done with Dawn. xD
And as for Brock, I think he's going to appear in the last few episodes of the B/W series. Y'know, to join Ash again?