We all know how the legend ends, with Arthur killed by Morderd and took to Avalon where one day the legend says he'll be back again. But Having Arthur killed off at the end of the season 5 of the BBC show Merlin, would be a huge mistake and too painful to watch. First since this is a family show it's not an appropriate way of ending the show, also wasn't Merlin supposed to be before they were famous? which means that the death part should not be mentioned at all. Of course these are only speculations and we not know anything for sure but It's better to let the producers know what we don't wanna see before it's too late.