I think Mattel's legal team won't allow Toyguru to make such a statement because ultimately, Bowspearer, you're right; Mattel can pull the Four Horsemen from MOTUC at any time. Sure, it would likely kill the line but legally it wouldn't be a breach of any contract with us. Unless there are specific MOTUC clauses within their contract with the 4H, Mattel has the right to allocate its resources in the manner that they see fit. Technically, the risk of losing the 4H's involvement with MOTUC has always been there.
The only reason that I don't sweat it is because the 4H have remained on-board since the beginning (2008?) without any indication that they've ever been on the chopping block. They've become the foundation, heart, and soul of MOTUC and Mattel seems to at least acknowledge that they are vital to this niche line's profitability. The BttF license, on the other hand, is a new one for Mattel, without a signature or tenured design team, and probably a lower priority to them than MOTUC. Chances are, the Hoverboard will be the only BttF item they make this year. (I don't follow this brand, so I don't know if they've made other plans with it) If it fails, I'd guess it's just a quick business loss for them and they'll move on...MOTU means a little more to them than that. (I hope, heheh!)
I still stand by my prediction that of all the things to worry about, the Horsemen's continued involvement on the Castle Grayskull project is one of the safest bets. I'd say that "Blastic" is a bigger threat if it continues to show up in 2013 figures. Everything is subject to change but at the end of the day, a 6"-scale MOTUC Castle Grayskull will be the final product if the pre-orders go through and that is worth it to me!