What would the wheel do otherwise? I don't want the scroll wheel to pan vertically. I guess doing nothing is acceptable, but I honestly zoom enough that I actually prefer the one handed action on my computer. I probably would just go back to double clicking if scrolling to zoom required a modifier, and that's worse UX because there's all sorts of stuff I could accidentally click on when double clicking to zoom.

If they do choose to go with a modifier, I hope it's not control, because I hate accidentally zooming the page with the browser's zoom since it breaks nearly every page out there.