Sure. I simply put the Send hotkey and Image exists activities in a Do while activity.
The hotkey I kept sending was “End” to make sure it scrolls to the bottom of the page. For the image exists I made a screenshot of the message “Loading messages…” (due to the fact that I think every webpage which uses this way to load more results shows some kind of message while loading them, this should be universally applicable). The condition for the Do while was the result of the check made by the Image exists activity, which outputs a boolean variable. So as long as the variable “MoreResultsAbailable” (=variable name of your choice) is true, it will keep sending the hotkey.
Once all results are loaded the Image exists wont find the image any more, “MoreResultsAvailable” is false and the process will continue with whatever it is supposed to be afterwards.
Hope this made things more clear