Xavier Garcia, a former MySims concept artist shared some concept art for a new MySims game that was set to be released after SkyHeroes. It looks like a reboot of sorts. And from what it seems, is like Sims 3 but with MySims as characters. It appears that it would have had cars, an open world and terraforming. This game also appears to have a brighter tone, as recent MySims games appeared a bit more darker.
Such a shame it was never released, my little cousin loves MySims!