Unfortunately it's not a case of porting 20 year old FSX textures into MSFS, never mind recoding all the gauges, recreating the models and redoing the animations.  MSFS started slowly without a lot of the abilities needed in the SDK to create a complex airliner.  I don't believe that's the case now. If CS are a small team, they will surely struggle to create great looking content for MSFS - it will be a huge investment in time and money and time is against them, if they want to leverage the following of their current customers.  P3D will eventually be side-lined as more and more investment from all the big companies goes where they can make money, MSFS and CS will see their revenue stream getting less and less.  Like it or not, unless CS can also make that move into MSFS, I'm resigning myself to never seeing my beloved 707, 727 & 737's shine as they might in the 21st century.  MSFS will solve all the problems they have.  Arguments over which is best will always be subjective, but one thing will always be true - Follow the money and that's behind MSFS, not P3D.