Ya, it's just potential and it's not worth billions but it's not worth 0 either.
There are numerous companies in Northwest BC that have potential. Romios Gold, Paget Resources, Teuton, etc. All of them can be bought for a few million dollars. I don't think the potential will affect the buyout price by a huge amount.
Do you really think that a few infill drills will make them go "let's manage our risk with 20%" to "we should buy the whole thing!"
I'm expecting the $85M will cover more than just a few infill holes. It will allow them to do extensive exploration drilling, additional metallurgical testing, further work on the environmental permits, etc. None of these improvement opportunities can be quantified without spending additional money.
My logic is based on the fact that I don't think we have enough info to make a construction decision yet. Backing in for 20% allows Teck to explore improvement opportunities without committing to construction. Essentially it delays their decision and allows them to improve the project.