And it's also possible that resolving the issues between relativity and quantum mechanics will have no implications relevant to FTL and such. In fact there's no particular reason to expect that it would. So we're back to just flat out speculation.

That's fine by itself, I love speculation, but that doesn't make this or that probable. It's the extending such speculation to making high confidence definitive statements, as though something's been demonstrated or proved likely, that I'm objecting to.