I think that what many of us tend to forget is that the Rabbonim of yesteryear were the MODERN rabbonim of THEIR time. Certain halachos are subject to an interpretation in light of the information of the particular time. For example, we now know certain things about the function of fire, electricity and laws of physics, that have affected how our rabbonim look at the SHABBhot water heater. We have a k’deira al k’deira that many poskim hold can be used to heat food up on Shabbos. As our poskim become better educated in secular areas, they are able to apply that knowledge to fit in with our Torah standards (not the other way around). 200 years ago, our gedolim did NOT know some of these things, and they paskened according to what they knew in those day, their own modern Orthodox times, for want of a better expression. Nowadays, we have halachos about organ transplants from both corpses and live donors, what denotes cessation of life, brain death, is artificial insemination an halachically-viable method of impregnating a woman who cannot otherwise conceive, and if it is from a donor is it considered to be mamzerus…etc. etc. etc. And while many of these things were known in the times of the Talmud and are discussed in the Gemarah, many fine details were not known until recent years.
If chalilah moshiach has not come in 200 years, I am sure there will be rabbonim who will know things that science has not yet discovered, and which were not yet discussed by our Rishonim. And our own present day sages will probably be regarded pretty much as we regard those who preceded them two centuries ago.