I doubt it, just because new options will have cost associated with them, and Tesla is not going to include that for free. I would assume you will get what you paid for and nothing else. If you're serious and expect any new gee-whiz feature they come up with before they build your car to be included, get it in writing from Tesla. At least ask them straight out if that's the case. No sense in being disappointed.
To the original question of this thread, I vote wait, at a minimum until the X comes out. Drive the X. Look over its options. You'll know a lot more than you do now and can make a much better decision. I bought in May, not knowing the 90 battery was coming. There's always something new cooking - wait as long as you can stand it, then buy!
Didn't the Autopilot hardware become standard and just start showing up? I remember hearing people got their cars delivered before Autopilot was even unveiled. I'm pretty sure that standard features will be included on future orders if they are standard at the time of the build. Same thing with LTE. They aren't going to install 3G on it if you ordered before LTE became standard.
I do agree with waiting though. I won't be making any order or confirming my reservation until after the X has been unveiled. Even then, I might wait to see it in person before placing my order.