In theory there must be a limit defined by the laws of physics, but we haven't even scratched the surface. If there's a limit to what's physically possible, it doesn't look like a cooler phone or a better therapy for some types of cancer, it looks like artificial superintelligence, full-fledged molecular nanotechnology and atomically precise manufacturing as described by Drexler and others, mind uploading and radical enhancement, matrioshka brains, cosmological lifespans, Von Neumann probes all over the galaxy and beyond, that kind of thing, and probably lots of stuff we haven't even thought of yet.