The Tokina 16-50mm f/2.8 DX appears to have been hard to find even when current, especially in Canon mount. Community experience suggests Tokina distribution can be uneven: major retailers may not stock older or less common models, while used markets and some Japan-based sellers are more likely sources.

For image-quality research, Lenstip is specifically mentioned as having a thorough review and background on the lens. Based on the answers, the safest conclusion is that availability is the bigger issue than performance.

Compared with the Canon EF-S 17-55mm f/2.8 IS, the Canon is generally the more mainstream, easier-to-find option and includes image stabilization, which the Tokina lacks. The Tokina may still be a viable alternative if you find a clean copy at a good price, but you should expect to search the used market or specialist importers rather than common large retailers.

So: yes, it can likely still be found, but mostly through second-hand channels or Japanese sellers, not typical big-box photo stores.