I read it again and I think its another carefully crafted statement. The POTUS says that Trump signaled a future in politics but not necessarily through elected office.

“Our historic, patriotic and beautiful movement to Make America Great Again has only just begun,” he wrote. “In the months ahead I have much to share with you, and I look forward to continuing our incredible journey together to achieve American greatness for all of our people.” so you could say he's signally he is out of the White House etc.... but reading between the lines and He isn't saying that at all.
So I'm still in till the last hand. ?????