Slaphead
500+ Head-Fier
Will this usurp the T1 as the main flagship?
I doubt it - Beyer runs two headphone product lines, consumer and professional. This will be the professional flagship. I don't see the T1 going anywhere and it will almost certainly remain the consumer flagship.
Beyer also tend to be quite strict regarding it's dealer channels - the HiFI dealers will have access to the consumer range, and the pro audio dealers will have access to the pro range (There are some dealers that do carry both, but they tend to have both a HiFI and pro audio section). For example I had to go to a pro audio outfit to get my DT1350s as the usual HiFi shops didn't have it, and, as was explained to me, couldn't stock it as they were not pro audio dealers.