what will be the excuse when the james webb sees past the edge of the now known universe...
It should see farther than any other scope, I think. It is more of an IR telescope than the HST. Since the more distant a galaxy the more redshift we see, then it should be able to extend our view of the more distant galaxies with its ability to see better in the IR band.
But the CMBR (Cosmic Microwave Background Radiation) that we see comes from distances greater than any galaxy. The redishft is about 1089, IIRC for the CMBR, and distant galaxies are not much over 12, I think.
There is hope that a neutrino "edge" will be detected someday. The CMBR came about 380,000 years after t=0, but the neutrino blast was very close to the beginning.