http://www.neogaf.com/forum/showpost.php?p=146833496&postcount=458
There likely will be more games in 2015 than the ones we're teasing. This probably isn't our entire year's lineup. I think the extra question marks represent the possibility of other 2015 titles down the line. Hatsuu's tweet is more to keep you guys from killing yourselves trying to find meaning in background patterns that are literally just background patterns.
In other words, our tease is only for 4 games, not 8. But that doesn't mean there aren't going to be 8... or 12... or 16... or 20... or 2... or -7.33 repeating.
;)
-Tom