I would push for year 2 next year, and let him repeat then if he's not ready to advance. I really think that in most cases it's best to fix the problem at hand (doing too long in year 1) than anticipate future problems too much. Afterall he may well surprise with his development in a year. Also at 98.8 you might be able to get an IEP for writing like using a lap top if he's not up to speed. Good luck!