That article is rife with factual inaccuracies.
The Windows Phone 8.1 Preview for Developers is, for all intents and purposes, the final version of Windows Phone 8.1. It is not a beta version, and although bugs can (and do) exist, calling it "likely to be buggy" is misleading. The only substantial difference between the dev preview and what will be released later this year is the carrier- and manufacturer-added firmware updates. And the delays associated with those firmware updates is precisely why Microsoft launched the dev preview programme - so interested consumers can get their hands on the latest and greatest as soon as possible. (Well, that, and developers being able to start testing their apps with 8.1.)
Yes, it's true that if you upgrade to the dev preview, there's no way (or at least no easy way) to go back to a previous version. It will not, however, affect your ability to receive future updates, including those from your carrier or manufacturer. Should Microsoft ever "discontinue updating its software with this app", that would just mean the end of the Preview for Developers programme, and it certainly doesn't mean anyone who installed the preview would be stuck with it.
For more information, see All you need to know about the Windows Phone 8.1 'Preview for Developers' at WPCentral.