Any one of those would be a major challenge and a major achievement to lick. While I totally admire Elon Musk for challenging all these things at once you have to wonder about the wisdom of it all, especially when taking into account that he has another major project (SpaceX) that would normally be enough to tax any CEO.
Furthermore they decided to roll Solar City into Tesla which makes Tesla even more encumbered with debt. I get why he did it but I firmly believe that cross-tying losing businesses and winning businesses at that level is a failure prone strategy, it is gambling rather than managing.
See https://news.ycombinator.com/item?id=16612805 for example.