This sentence is ridiculously complicated. What made it so?
Until last week, I would have said that your best hope for being more than a bodiless brain in a chemical stew was the fact that no scientist was yet capable of sustaining a viable brain in a jar.
I kind of know what it means ...
"If you want to be more than a highly-developed brain in a jar, then your hope is dashed because it's not even possible to sustain life in a jar in the first place... at least that's what I would have said... until last week."
Am I right?