Honestly, I don't see that happening. Theres a chance, but I think the folks that make up HTC are better than that. Besides the 2 arena's won't be soo different from one another that one will draw more resources causing the other to suffer, all arena's use the same AH engine. If you think about it, as it is now all other arena's are merely a subset of the Main arena providing player driven niche gameplay, training, and player driven scenarios. With AH2 it seems that things will stay the same but we'll have new code and a beefed up CT seemingly making all arenas a subset of the AH2:TOD arena.
Could it happen, yeah, but the concept of AH2:TOD won't be extremely different than what we have now, minus the upgrades.