You face a big issue there. Meltdown is a core architecture issue. It will take a long time to make a fix. Add to that the need for a completely new branch predictor (a notoriously hard design issue) and you're talking about a lot of time. Intel and AMD should already have next years designs done (AMD has said as much with Zen 2). You'll most likely be looking at late 2020 to early 2021 before the fixed architecture is thoroughly tested, taped out, and being produced in volume.