"This statement is unlikely" - Can it be false? Can a statement be un/likely? I'm just going to start with that, because I'm not sure in this case what that means. Do you mean that: "This statement is unlikely to be true?" Sentences or statements can be true or false, or provable or not, but I'm not sure about "un/likely", other that its "un/likely to be true/false". So in this case, is the sentence unlikely to be true or unlikely to be false? Because that might change the resulting statement. (The other option of "un/likeliness" I thought of was "this statement is unlikely to be in existence" and I'm not sure what to do about that, or if its nonsense)
As for: if "it is false that "this statement is unlikely (to be true?)"" resulting in "it is not unlikely(to be true?) that this statement is unlikely(to be true?), I'm not sure they are equivalent. One seems to be a statement about another, self-referencing statement, and the other is a related but different self-referencing statement. That may result in some confusion. Also, in this case, its not clear that the two "unlikely's" mean the same thing: again, you'll have to clarify. Is it "unlikely to be true" that this statement is" unlikely" or "unlikely to be true"? Or is it unlikely to be false that this statement is unlikely to be false? (or any other combination)
Whether it is a contradiction or not depends on what you mean by "unlikely". If a self-referential sentence is attributed a truth value, it must reference its own true value to be able to lead to a contradiction. "This sentence is green" can equal true or false without resulting in a contradiction.
The final "its is unlikely(to be true) that this sentence is unlikely(to be true)--(I'm just going to assume you mean this) does seem to pose some sort of problem, but I'm not sure, as you are, that it leads to a contradiction, because the "unlikeliness" has some sort of "degrees of true and falseness" that aren't as black and white as traditional truth values. So you don't exactly have A and not A, but more of a probability that there is a probability of A.
It seems like you are dealing with some form of fuzzy logic, but I'm not well versed in that topic, though I've read a little. I'd love to tackle the logic of this further, but currently in that I am a novice. Hope this helps some.