That doesn't make any sense. If WotC doesn't add a monster to the SRD themselves, then it has to be licensed out, Tome of Horrors style. TOH sold because WotC didn't publish those monsters previously. If they release MM2 and don't add it to the SRD, no 3PP is going to license those monsters just to add them to the breadth of open content. Why would a customer buy a 3PP book when they can get the exact same book with the WotC name (and presumably the WotC seal of quality) on it? That will be a considerable amount of work for nearly no money. It'll never happen.
Effectively a no.
No, I am suggesting that WotC begins putting the OGL in their own material, as they did with Unearthed Arcana, only with the monsters.... They do not
need to add material to the SRD in order to make it OGL. Nice when they do, but not necessary. A publisher could then use, say, a Sootbelly Kobold in their setting, then add
only the Sootbelly Kobold to their data pack.
As for 3PP adding the critters en mass, I don't think that they would, except in something along the lines of Monster Geographica. (Still my most used monster reference, outside of the PF Bestiaries.)
More likely 3PP would use them in adventures or add them to a terrain/environment/region book, sometimes as specific named creature, then add only the critters that they actually used to the data pack.
That said.... Let us instead say that WotC adds them to the SRD data packs, instead. That they find a way to use the stat blocks out of the files used for the books instead of adding critters by hand. (I believe that currently they
do add things by hand, but I could be wrong.)
Sorry if this is sounding vague and disoriented - I played 24 hours of Skyrim, fell asleep, and just woke up.
The Auld Grump, and now I want to go to bed again....