Apart from the Vega...
If that's the case, then maybe there would be an opportunity to re-invent 4WD. Cheaper, less parts and better performance
Might be a tough challenge but those ones yield the best rewards.
Even if they release a 'normal' take at the 4WD, it's still a profitable product and 'completing' the 10th scale lineup has it's own advantages. Brand representation in all classes (which makes the brand better known to areas and clubs that do drive 4WD more). And like good parts support, TLR owners may also consider the TLR 4WD over other cars being a TLR (if you don't offer that, you're assured that that doesn't happen)
I understand you have to consider profitability, but only selling the big ticket car(s) in the long run isn't going to help the profitability of your company (people lose interest in that small lineup you have with a lack of diversity), and it could ruin your income by the time that the popularity of classes starts to switch again.
All that said, I don't see TLR coming up with a 4WD very soon... I would love to see them do it though!