No personal offense, but a lot of this sounds like excuses.
If TMMF becomes too unprofitable, then Toyota will either dramatically shift production or close the plant. Nobody here said that the Yaris somehow is a big profit maker. It's well known Toyota makes little to no profit on the Yaris currently. However that's part of the problem with the current generation Yaris/Vitz; there aren't any top level trims like rally style or hot hatch variants, which would bring in a lot of profit. The only exception is the super-limited volume GRMN Yaris.
It is not excuse, it is now car business works and how it has always worked. This is why you have Mazda 2 in USA instead of Yaris Sedan.
You are looking at it from enthusiasts standpoint, who always wants something new... it is not going to happen, and it is not happening with competition either.
They have plenty of expensive versions of Yaris in Europe and they are doing extremely well with it, as sales are constantly raising.
Nevertheless, when you mention how it is delayed, lets reserve that for when Toyota has delayed model from specific time frame, and not enthusiast point of view where they have to release new car every 5-6 years.