Is Safari becoming the new IE?

No[1].

SPDY support would be a nice-to-have, but the problem with today's websites is that the vast majority of your resources are external; ad networks, like buttons, and so on. It's is great in the optimal case, but in the typical case it doesn't make a significant enough difference to bother supporting[2].

The other two issues (NavTiming and WebRTC) would be really useful, but for a minimum of web developers or applications, so I can understand them not focussing developer time on it. It'll come soon, but the Safari team was pretty small last time I checked so it's no surprise it's not a priority.

    [1] http://en.wikipedia.org/wiki/Betteridge's_law_of_headlines
    [2] http://www.guypo.com/technical/not-as-spdy-as-you-thought/