I think that is a pretty good idea, although if it is but mentioned most people will just ignore pi in that case, like most people just forget things they don't really use. They are like the rarer punctuation rules in grammar, which most people to a large degree forget. So if pi and tau are both used but either is more prevalent, people would soon forget the other and wonder what on Earth it is when they see it. Of course there are conversion tables and booklets for this stuff, so this is not such a big issue.
I don't think this will be changed either, convention is a menace.
I'm still fine with that. If they were to go about the whole change process, it would have to be like that. Have a mix of both, and then see which one holds out in the end. That way, the entire world isn't forced to stop and re-program their brains to accept tau, since I can guarantee that I would botch up and end up writing something akin to sin(tau/2)=1.
Since, in my opinion, if they want to go about making this change, might as well change the whole number system to make it more conventional, as I mentioned previously.
That tradition is even more confusing since split-complex numbers (or perplex numbers) are of the form a+bj, where j^2=1, but j isn't equal to 1. On the other hand, due to the lack of available symbols (or rather the non-use of other than Greek and Latin ones) we have already come across that problem many times over, I mean just look at this list:
http://en.wikipedia.org/wiki/E_(disambiguation) It is still a problem though, perhaps we should start accepting Cyrrilic symbols?
Indeed, I am aware of this. And not being in electrical engineering, the entire process is confusing as heck. (Although, not as confusing as, say, biochemistry, and their half a dozen various unrelated usages of alphas and betas...it's as if they didn't even try and just got lazy. xD No offense to any biochemists out there...) Indeed, I believe we should be doing more symbol alterations similar to h vs ℏ, as well as other alphabets. Or heck, just make up a symbol.
But alas, this convoluted melting pot of all mathematics and sciences will never get itself straightened out, no matter how hard people try.