So after many years of rumours (I remember hearing about it back in 2012) it would appear that Yaesu have a new radio in the pipeline to replace the FT-817.
Documents for the Yaesu FT-818 have appeared online which appear to show that the new radio is undergoing testing with a view to launch later in the year.
As you can see the documentation shows a radio which can cover 0.1 - 470Mhz.
The actual bands are said to be:
000 - 030 Mhz
050 - 054 Mhz
076 - 154 Mhz
420 - 470 Mhz
Further information will appear HERE and the actual radio is expected to make its first appearance at the Tokyo Ham Fair in August this year.