A 1.4x TC would give you a ~50-140mm lens. Which is essentially covered by the already well regarded Oly 40-150, only faster. While it would be nice to extend the compact 35-100, it just doesn't seem that marketable to design such a TC just for that one lens. I won't even bring up a 2x TC
It wasn't designed for a rear mounted (protrusive element) TC.
You could wing it with a very, very good front mounted teleconverter but those are highly dependent on the lens-teleconverter combo. They also require you to thread them on and you'll have a longer minimum focusing distance. You also need a front element of at least 50mm for it to stay f/2.8 at 140mm.
I had the Oly 1.4x and 2x for 4/3 and used them occaisionally with good results. I'd love to have a 2x that I could attach to the Oly 75mm. It would be more compact and lighter than carrying another lens to get out to 150mm.