ReWire alternative/solution (4 years later)?

Unfortunately, I don’t know of anything that provides the same functionality that Rewire used to. Another user in this thread

was able to get some use out of a plugin called Rewire VST by XT Software.

But really, the idea of running Renoise as a VST plugin inside another host is very attractive to me, assuming they get the transport synch, etc. implemented correctly, and I hope the Renoise developers consider it.