I've used Palm products (Palm III, IIIe, M515, Tungsten T3) for years without sync troubles on my Macs.
I rely less and less on my PDA, using my PBook, iPod, and cell phone to track meetings and such. I doubt very much that there will be any new PDA device (like a Palm or an iPaq) on the market in five years' time. Cell phones and music players are converging from both sides and sucking up the low end PDA market in their vortex. The high end PDA market is getting challenged by newer, smaller laptops. Tablets have potential, but that market isn't developing all that quickly, and they might not even survive as a mainstream device. Sooner or later, someone will hit the sweet spot and produce a small, light, powerful convergent device that will wow the market. I suppose Apple has just as much chance of being that company as anyone else, but that device, when it comes, will not be what we think of today as a PDA.