Goes without saying that the more ambitious old tech designs will need to be upgraded with TE once this sea change comes to pass...
I'm also guessing that courses with added 3D grass will be incompatible with the older version of JNPG, so once the designers switch (which they undoubtedly will) then new courses will dry up for the original game, unless two versions of a course are released, as with the reflective water course by PP.