I think it's fine to think that 80 million is a fair development cost for an AAA game which could sell say, 5 to 10 million copies. What I do not think is a good look though, is if you feel that 80 million is a fair development cost given that it includes the development of a brand new engine. That is a factor which I think people seriously overestimate the value of.
If you have a huge pipeline of future games developed internally, and it makes more sense to develop an engine and toolset the entire company can use with full support internally, that might be worth it. An example would be EA using Frostbite. But if you're a company which is looking to reduce output on dedicated consoles, and only have a grand total of two big franchises which could benefit from such an engine left... where's the value? What would be the savings against just licensing a good engine like UE4 and going forward with that for the 1-2 games you're putting out every year? The investment in an engine makes no sense if that is the state of the company. Furthermore, by being willing to essentially let the developers of said engine depart from the company, it is a statement that the company sees no value in retaining a strong support crew for the engine and tools. This further reduces the value of investment in said engine.
If you ask me, I'll say that the outlook is that Konami is writing the Fox Engine off as a loss.