Interesting part of that is their was some thought put into the idea of bringing hayden in as a force ghost for episode 7 which you never know could still maybe happen in 8 but lets just talk about 7 for a moment, they clearly didn't forget about hayden, they had that option on the table as a possible use for him so just because he isn't back in the vader suit as a movement capture artist which he isn't essential for at all doesn't mean a hell of alot
To go back to recasting fett though, there is no point to recasting fett unless there is a reason for him to look different and then you have to take into consideration the prequels and animated shows so i dunno why you think lucas arts will try and move away from it, maybe wishful thinking on your part buts the odds are very much against you
