For launching things, Opus can have docked/floating toolbars, which can blend in with the taskbar. I have one on the bottom of my right-hand monitor, which looks like this next to the taskbar on the left-hand monitor:
That won't replace the whole taskbar, though, since it doesn't handle showing and switching to active windows, the clock, notification icons, and so on.
I am not sure it is a good idea to try to replace the taskbar, as it could be a compatibility nightmare. I suppose the real taskbar could be set to auto-hide and something similar shown instead, which would be safer.
What value do you think we could add that the real taskbar and other alternatives do not already provide?