Now that we have sponsored tags, the system surely knows that those tags have the same sponsor, so can we have auto-generated sponsor tags? That way I can just follow everything sponsored by Adobe or Microsoft or whoever, including any new tags they sponsor that I didn't know existed yet but might be useful.
I am not so sure the system knows they have the same sponsor, in that the sponsor data may be denormalized. That is, the data may be in there somewhere, but if it's embedded as part of other "tag" data, then it might not be immediately usable for querying as you suggest.
If it is, though, the same mechanism could be used to support more generalized tag hierarchies, as suggested here. While the dev team have declined tag categorization in the past, now that they have done at least some of that work to support sponsored tags, perhaps the idea is more viable?