Most of them are probably at maximum capacity, anyway, but if Wessex is blended by K&K (and I think they are) then perhaps there is a little more room to grow than if they were a standalone operation...
Not to dispute your theory, roth, because it is accurate time and time again in other industries, but we have been fortunate in the pipe tobacco world to see quite a few successful transitions.
I think we are all glad that Dunhill and Erinmore are being produced by STG rather than if they had to go the way of the Dodo with Murray's. I do not hear too many complaints about the new products. Escudo has changed hands numerous times, but it is still a high quality blend even if one can argue that its not what it once was. I think that companies like STG have been a blessing for the pipe tobacco industry. Even K&K is keeping venerable names like Rattray's alive even if what were once straight Virginias are now spiced up with Kentucky and Perique to compensate for their shortcomings...
Even FVF isn't what it once was either since the Zimbabwean leaf supply disappeared but that doesn't stop many people from searching far and wide for a single tin... (This is a little different as they are still a "boutique" producer as opposed to a conglomerate but you see what I mean!)
On the other hand, if a prominent cigarette company buys a pipe tobacco brand, then it is time to get nervous. Quality will begin a steady process of decline and you can bet that the weaker stablemates will be up on the chopping block if they inevitably fall behind on their sales quotas...