A clear one would be that the integrity of UK democracy would be severely damaged. If I understand correctly, the only way of leaving is using that article so not using it would be to not hear what the people said in the referendum.
That's 52% of the turnout; 38% of the electorate; 25% of the population.
They won the ballot, but I wish they'd stop saying "a majority of the country voted for Leave" when only a quarter of the country voted leave.
You can't say a majority voted leave as such, but you also can't say a majority wanted to remain. The only factual figures we have suggested a majority would have voted leave.
That's why this kind of referendums should ether be mandatory or have a higher approval point(like 75%)
Now, those 16m that didn't vote. Do we know if they don't care? Or if they are against or in favor of leaving?
Also, many would say that if you don't use your right to vote, then you can't complain about the decision taken.