I think the BBC are in a 'promote women' drive (Mishal Husain got the R4 Today job ahead of Nick Robinson) and promoting Tess to permanent main host of their prime time Sat. eve show would be seen as a good move by the Corporation.
She did a great job on the recent Sport Relief minus Bruce, and when teamed up with Claude, they have a natural rapport. She's certainly better in the lead role than in the Tess Pit where her questions are cringeworthy sometimes. Claude is obviously never coming back to ITT (let's pray Lisa Riley doesn't get that job eventually).
Ultimately I think Bruce will dictate terms and keep his role for about half the run, including the Final ofcourse. It always amazes me how we have a big exciting build up to what we hope is a great show, and Bruce stumbles on, mumbling and not knowing what his cue is. It's embarrassing and kills the excitement stone dead, and yet the Producers can't see that there's anything wrong? Though I agree with others, he obviously is a Dance aficionado and knows when the standard is high and is excited by it.
I thought Graham Norton was great on Strictly Dance Fever, but that was a different show. Whether he'd take on SCD or even be asked, who knows? But I think he's the only other alternative. It's a long run and a big comittment.