Best guess- the next parallel to the adoption of HDTV
Whether 3D TV will become standard or remain a novelty is an educated guess, and there are always a dirth of opinions and punditry to go around. That said, I feel pretty confident with my own prediction, that it will mirror what happened from 2000 to 2010 with HDTV.
In 2000, HDTV was largely something one heard about but never saw, except on display in tech stores for exhorbiant prices. Those few wealthy early adopters also had little in the way of anything on HD to watch. Furthermore, there was a format war between 720p and 1080i. Those people on a budget might have even settled for "Enhanced Definition TV," or EDTV, which, in a nutshell is basically a set that could receive 720p and 1080i but only display it as a 480p image.
Contrast that to today, which as of this writing is in 2010. All TVs pretty much are HDTVs; you can't find anything less than 720p even for a bookshelf set. Neither 720p nor 1080i became a dominant standard; the even higher bandwidth 1080p looks to be the universal standard, though every set these days has to be able to receive all three formats, even if the smaller models are not yet showing all 1080 lines of resolution. More importantly, we have a slew of technology standards today that the first HDTV sets lacked--most notably HDMI. HDMI ports allow all-digital transmission of high definition content, even throwing multi-channel uncompressed audio in the same pipelines. The few HDTV sets sold back in 2000 had no HDMI inputs at all, and my first set, from December 2004, had only one. As for content, my satellite service gives me some 30 or 40 channels of high definition content, and my regular shows are pretty much all HD now--and many of them are off the beaten path, on cable channels like Syfy, Comedy Central, and BBC America, rather than the major networks. (Granted, if you live in the UK, BBC happens to be a major network. But, here in the U.S., it's a niche.) The 1080p capabilities of our biggest set also gets put to use showing Blu-Ray movies and PS3 games.
Today, 3D TV sets employ various different proprietary technologies to display the appearance of 3D images; all of which right now require compatable glasses. One cannot take a pair of glasses from one system and use it with another. There is talk in the works of sets that are autostereoscopic--that is, show a 3D image without glasses. They have been demonstrated at tech fairs, but they have yet to make it to market. 3D sets are marketed in tech fliers for places like Best Buy, and are bundled with sets of glasses and a copy of Monsters Vs. Aliens, a recent film released in 3D. There are about one or two dozen other movie titles available in 3D, but it will be awhile before there are very many. Conspicuously absent from the lineup for now is Avatar, one of my personal favorite movies in decades, and perhaps the breakthrough movie for the 3D format.
My hunch is that, ten years from now, TVs will all be autostereoscopic, with the option to turn off this feature if you're one of the unfortunate people who gets headaches from it. Most major networks will broadcast it--assuming they still exist or that people still subscribe to TV rather than download it off Internet services by then. (In this case, it will be large computer screens, oversized iPads, or some other thing technically rather than TVs per se that are applicable.) Avatar's tenth anniversary edition will certainly be in 3D, but I'll have already bought it again one or two times before by then in 3D. The sets from back in 2010 or 11 that came with glasses will by then be obsolete.
But, there will always be a little better just around the corner. If you wait until my prophesy comes to pass, assuming I'm even right, you'll potentially have missed a few years of enjoying 3D in the mean time. 3D sets from today may be doomed to obsolescence, but, in the tech realm, so is just about everything.
I'm waiting for now, though. Monsters Vs. Aliens was a cute movie and kind of fun, but my wife and I saw Avatar in the theater six times; we didn't even see Star Wars that often. Until there's more actual content to watch in 3D, there's very little reason to shell out so much extra for something that will almost certainly be either a whole lot better or a whole lot cheaper by the time there's something good on.