Luckily, unless the TC 14e iii offers such a massive step change from the previous TC14's, anyone actually affected can just use an earlier version.
I have the TC 14e ii. In fact if anyone here needs this, I'd be happy to sell as I can't remember the last time I used it.
For anyone in the UK, you can have it for 170 plus postage. Pretty much v.good condition with original box etc.
Happy to consider overseas, but the delivery will cost a little more.
Works well with a 300mm f4......