Well, that is what all the debate is about, isn't it? Just expanding polaris to 64CUs, 512bit GDDR5, and running at 1400MHz would be a bit smaller than Vega, wouldn't draw more power, and would perform much better than we have seen so far. So why Vega, and more than a year later?
I'm not comfortable with the assumption that AMD graphics folks are totally incompetent however. I hope AMD introduces Vega properly, explaining their design goals, the features of the new design et cetera, giving us something better than just a few puzzling benchmark scores.