> This pricing isn't really accurate, as you can also sign up for Unity's subscription service, which now has no set time limit on how long you have to sign up for. So, you could create your entire project in Unity, for free, and only sign up for the subscription to push it out to platforms outside of OSX/Windows/Linux. I've easily saved thousands of dollars using their subscription service instead of buying each major release outright, as was required previously.
So that means implementing Pro's features last-minute then, huh? Because Pro has some really nice stuff packed in that Free lacks. I guess it's not a big deal if you already know what you're dealing with but of the Indie devs I know, they'd rather outright save up for Pro and not have to worry about the rest.
You can keep the monthly account for as long as you'd like, and given Unity's recent upgrade cycle length is more bang for your buck than purchasing outright.
As for missing Pro features: other than internet multiplayer/networking they're almost entirely graphical, so even if that means you're paying $75/mo for, say, 3-6mo to add those graphical features you're still saving a ton of cash to put towards another part of the development process - mobile licenses, for example. I can't really comment on how long it would take to add the networking stuff in, and I can't say I've seen a ton of Unity (or Unreal tech in terms of indie dev) that really use it anyway.
I've been using Unity since the first versions on Windows (2.x somethingorother) and their current monthly pricing plan is by far the best deal I've seen in terms of providing access to powerful game (and other) development tools at a more indie-friendly cost. And what with the company's general responsiveness to their community - far more than Epic/Unreal's actual day-to-day engagement - if someone were looking to make a 3D game, Unity would be my first recommendation.
For 2D, I'll still push C2 over Unity2D any day. With Scirra's very supportive, mostly friendly and knowledgeable community it's a total no-brainer, not to mention the awesome and personal support their team provides.