season 2 was confirmed already. filming starts next month in the UK.
i don't think they will cancel after just 2 seasons. they've spent far too much money on it. it would need to be really bad for them to do it. i think you'd be getting way ahead of yourself, 2 episodes in, to say it will tank. it seems like people want to hate and shit on the show. that was always going to happen but it seems like most people are enjoying it.
edit: also it seems amazon agreed to 5 seasons as a condition to get the rights from Tolkien Estate. if they don't honour that then they could having legal issues with Tolkien Estate.