There are demethylation agents. The problem is that we need very specific demethylation of those areas involved in PFS (if this even proves to be the problem). We do not want to demethylate areas not involved PFS, afterall Methylation is not generally a bad thing. Since we do not know yet which areas are involved in PFS, it is impossible to say whether there will be helpful agents. There are also other things going on in science including epigenetic editing with CRISPR. These tools are not yet at a stage where they can be used in humans, but their development is advancing rapidly. Hopefully, one day they will become an option.
Anyway, before we have a clear idea what is wrong with us, it is all speculation. We just don’t know.