Imagine this happens: RCMP tests the sealed water bottle and finds the pair's DNA on the lip. RCMP never finds any other trace of them and abandons the search, declaring them missing and presumed dead. Would you be satisfied with that? That would be good enough for me. As soon as I read "rowboat" and "rapids" and thought, no trace of them for 12 days and well...I'd be pretty willing to accept that the river got them.