MIAMI – Don’t count Dwyane Wade among those who believed the Celtics’ competitive tenure was coming to an end last June. While the horde of reporters surrounding him scoffed and giggled as he said the Celtics would continue with their current core for three more years, the expression on his face remained serious. He wasn’t joking or being overly laudatory.

And here we go, nearly five months later, the defending NBA champion Heat opening the season Tuesday against the not-so-ready-to-start-over Celtics at ­American Airlines Arena. The Heat are hardly surprised that their primary rival decided to retool instead of rebuild.