Predicting energy futures is very hard. If you look at the quality of the historical projections, they were extremely inaccurate. My personal judgment is that the chance of meeting those targets is very low, but I don't actually have a lot of confidence in my own judgment. It's also important to say that the targets are fundamentally political. They don't come from some cost-benefit trade-off. They're not actually what scientists say, and I'm one of the scientists.
It's also important to say that economists do not actually say that carbon pricing is always the most efficient thing. That is not what careful econs say, because it is only true in a world where technology does not respond to prices. If you have an economic model in which technology is what we call exogenous—doesn't respond to prices—then just going up from the lowest price to the highest is the right thing. But in the world we actually live in, which is much more uncertain than the world of those models, it is not necessarily true that carbon pricing is the most effective thing, and maybe in some cases and not in others.