the invention of possibilities, though unrealized in practice, is the #1 cause of UI erosion through feature extension.
we have yet to run into the possibility you highlight on devices. note that on desktop it is common, and the workflow there remains as it always has been as a result of that.
(this is why it is so important to keep in mind that we design for different F+I+U [form factor + input method + use case] when creating different Plasma Workspaces. yes, they share 98% of the code and are highly interoperable .. they also present different workflows appropriate to the F+I+U tupple. so the touch focused UI works differently from the desktop one in this case)
as for the touch case .. if we find that this indeed becomes an issue on tablet as well, then we will address it in the UI there. my expectation would be to go the route of something like "long tap to select an alternate viewer", but that's just an immediate thought pulled by from my rear facing protrusion ;)