While it's nice to see BMW getting into another racing series, I give modern DTM a big meh. Given that the cars have many spec parts, and are shells over tube frames, I'm not sure the series is any more relevant to road cars than F1. The biggest difference is there are better cost controls in DTM, and the cost was likely BMW's main reason for leaving F1.
I'd actually rather see BMW start a serious LeMans prototype effort than get into DTM. That would probably cost almost as much as F1 though.