Gentlemen,
While it is true that the newer trains are engineered for a bigger layout design, 4x8 layouts are easily adapted to the newer trains. In fact my multi-level Christmas layouts fit on 4x8 and smaller Platforms without any problem. I use both FasTrack and RealTrax and cut custom close out pieces with my Rockwell X2 portable table saw, as needed to complete the track design. Using the correct track design and engineering knowledge 4x8's are still viable for our O gauge Train layouts.