There has been plenty of speculation and general agreement that QFT and Gravity may not mix. The most prominent argument given is that QFT perturbative expansion blows up at some level when dealing with the gravitons field. That is where string theory comes in and tries to be the bridge between QFT and gravity.
There are preliminary indications that the idea that QFT's description of gravity may not produce all those infinities after all. A new paper being highlighted in APS Physics this week shows exactly just that for N=8 supergravity.
This certainly would be a significant theoretical advancement, but probably under a rather restricted condition. But still, it shows the first indication that QFT may not necessarily automatically blow up under situation.
Coincidentally enough, a new preprint by Steven Weinberg appears today on ArXiv. It is more of a description on the history and development of effective field theory as applied to the strong interaction. Here, he too argues for the possibility that effective field theory of gravitation may in fact survive at higher energies.