Hypotheses can be proven true and frequently are.
Hypothesis: Tomorrow, so and so will pay me $100.
The next day, so and so pays me $100.
Hypotheses that are more theoretical in nature are harder to definitively prove. But they can be proven, and sometimes are, evolutionary theory being a case in point.
Of course, one can take the view that Martians planted those fossils or that they don’t exist and we are hallucinating them. But all of that only proves the point at hand; for if the rebuttal to a hypothesis is that we might be dreaming/hallucinating/etc., then that hypothesis is good to go.
There are also pseudo-hypotheses (e.g. karma restores moral cosmic equilibrium, etc.), which cannot be definitively established—but only because they are hypotheses in name only.
As for the ‘hypotheses’—discussed by another respondent—that there is a winged charioteer in the sky—-that definitely can be proved or disproved, unless special and artificial measures relating to its verification-conditions are taken, and, more importantly, it is so tendentious and non-representative or scientific or ordinary cognitive practice as to both non-responsive to your question and without force.
Of course, empirical hypotheses cannot be ‘proved’ in the same as purely conceptual truths, e.g. mathematical truths, but that is simply irrelevant, since, if that is what you mean by proof, then the contention that hypotheses cannot be proved collapses into the triviality that empirical contentions are not non-empirical contentions.
Instead of starting with obvious facts and working outwards, you started with a chic but totally spurious hypothesis (‘no hypothesis can be established’) and, taking that as fixed, worked inwards, with predictably raunchy results.
Finally, if you ‘know that the outcome is certain’, to quote your own words, then it seems it has been proven. So your question self-undermines.
Someone commented on my response saying that “correlation isn’t causation” and that we can’t ever know what (if anything) causes what. First of all, this is totally irrelevant to what I said, given that some hypotheses are singular assertions (e.g. Smith will still be alive tomorrow), as opposed to causal statements. Second, it is obviously false, and, as I told that person, has to do with acceptance of pseudo-empirical—but, in actuality, tendentious and highly theoretical—conceptions of causality, and not with causality per se. Sadly, the idea that we can’t ‘know anything’ is a magnet for small (and bitter) minds, and the time likely to be wasted dealing with them must considered before weighing in on questions about knowledge-theory, especially in public venues.