Assuming that the two "end's" is a typo, #1 is correct.
In number 2, you need to use the possessive form of the word "year." And it is usually considered good style to write out small numbers--perhaps 1-20--in words. So, "If we go on like this, there's no telling where we'll end up in one year's time." Or, "a year's time."
In number 3, the grammar is correct. As a matter of style and word choice, and depending on your meaning, it would probably be better to say "will" instead of "can." There is a small usage distinction between "can" and "will." "Can" refers to capability. "I can carry a 10-kg bag of sand." The word "will" expresses volition, desire, want. For example, "I hate avocados! My teeth are fine, I certainly can eat avocados, but I will only eat them if I have no other choice."