As far as I know, each CBS All-News stations (WCBS and WINS, KNX, WBBM, KCBS, KRLD, KYW, WBZ and WWJ) will all have in-house traffic reporters. Not sure about the larger market CBS talk stations (WCCO, KDKA, KMOX, KXNT). It's possible some larger CBS stations may cover smaller stations overnight and weekends. For instance, I heard WWJ is only hiring four traffic reporters, so obviously some non-prime hours will have to be done elsewhere.
Since the old call-in numbers went to Total Traffic offices, some numbers may be changing. In NYC, WCBS uses a 212 number while WINS uses 877, a toll free number. Both numbers currently ring in the Total Traffic studios near Met Life Stadium. So if WBBM begins using toll-free 855, that does not indicate the traffic reports will be done outside of Chicago.
Even though the final total isn't known yet, it appears many Total Traffic reporters currently heard on the CBS stations will NOT be joining the new CBS service.