Well section 5.4 should be easy to abide by
My first reading doesn't turn up anything about not using the
OGL anymore.
But you certainly couldn't mix
OGL and
GSL in a single product.
It seems that the license allows one to use the official logo and bunch of terms. The definitions of the terms are not in the
SRD, so I presume you cannot define them in your product.
Still subject to the whim of
WOTC changing the license and without the
OGL to fall back on this becomes a real risk especially for print publishers.
I think
WOTC really dropped the ball on the delay of the license. This is one thing that really attracted me to 3.0.
It will be interesting to see where we are in 5 yrs. Will 3.x be essentially dead, like 2e was?
I strongly suspect that 3.X will live on for quite some time.
I expect I will DM and play 3.5 for some time to come. Currently I am willing to play 4.0, but I don't have the time and the rules don't excite me enough to DM it. For me 4.0 will just be another 'flavor' of D&D kind of how Arcana Evolved is; not a replacement for 3.5 but something I am willing to play.