I asked the same question - and never got a clear reply - just information from the last time (I guess many years ago) when 4x10was aregular item.
I do shoot the other formats you mentioned... I hope tha Ilford/Harman opt to continue serving the weird sizes (7x11, 5x12 and 6.5x8.5) and add 4x10.
I have placed my order for the 3 formats and I hope that we can indeed continue to get film cut to rder every 6 mos or so. 4x10 would be the cheery on top. Let's see if we get a reply...