Depending on whether WotC cancel the d20 license or just quietly stop supporting it, we may see any and all d20-branded products disappear, either being re-issued as OGL products, or simply disappearing entirely. We'll certainly not see any new d20 products being published.
For OGL products, I expect we may see a raft of new editions from some publishers, as they take the opportunity to bring their games into line with the new D&D mechanics, and not coincidentally gaining the sales boost that comes from a new core rulebook being published.
And, in some cases at least, we'll see things just carrying on unchanged.