if wormholes were not empty and contained a small amount of matter, "exotic matter" that could exert an outward push on its walls then it might be possible to keep a wormhole open. it is similar to einstein's cosmological constant but the exotic matter would have a negative energy assosiated with it. BUT gathering so much exotic matter would be VERY difficult.
"Wormholes" are purely speculative concepts which seem to be possible under certain assumptions of General Relativity.
Experimental or observational confirmation of even the existence of such critters is still many lifetimes away (assuming advances in physics theory don't rule them out beforehand, e.g. from some discovery in M-Theory).