Now, before I write this article I just want to get out of the way and say that this is basically "theory hawking". 9/10 times when you judge the meta-game before a game releases...it's wrong, or off. I'll do it anyway because I'm bored.
So now that Starhawk is switching from base spawned vehicles to an economy based spawn, there is going to be a big impact on how vehicles function in the game. Here are my theories on how the Build n' Battle will effect vehicles and how they fuction as compared to Warhawk.
Let's go back to Warhawk, to the official serves. We're playing on Archipelago, CTF, on Acropolis Assault(right?). Also, we're using the broken mirror expansion pack, so this means APC's. Now, a lot of people don't like this map because they believe it is a slippery slope map. In other words, you capture the middle base and it becomes very hard to lose. However when playing on broken mirror, each team has an APC. Just one, uno. That is the only thing that if used properly can help you break the middle and capture it for your team, not to mention breaking into the enemy home base. It was just a damn useful all around. Except you had one, unlike the other large player CTF maps such as Eucadia, Badlands, ECT. That made that one vehicle so valuable it changed the dynamic of the game so much. One APC, if used right, could turn the game around and accomplsih so much as a forward spawn and portible super bunker. If you lost it...you had problems, or you were stuck on the defensive. This is how I think vehicles in Starhawk will be, not AS valued as the entire game rests on one unit, but they'll have a higher value tied to them because there is an investment behind each one of them, and since they need to be bought, there will probably be less of them. You can't just throw away vehicles and have them respawn 30 seconds later, they have value, you NEED to be cost effective with them. You need to justify their cost, or else it is going to cost you and your team.
Here's another way of looking at it. What happens when you kill a Warhawk in....Warhawk? You get a point...and that's it. That pilot you just shot down will just respawn and get another Warhawk from the junkpile. Okay, now we are in the future playing Starhawk. You shoot that guy in a Hawk. You get your points, that player respawns...but wait, he can't afford another Hawk. You just made a big impact on their air superiority, he now has to go get that one or two extra Rift-Energy on the ground. That may not seem like a big deal, but every minute you keep a good pilot on the ground (as we know from Warhawk) can be HUGE. Even if he can afford another Hawk, he's gotta pay for it, and if he's not getting enought Rift every go, he's eventually going to run out, or just not be able to get anything else, like an upgrade. Ofcourse there are 15 other players, but even a few players hit in their wallets like that can make a huge impact on the game in the long run.
Think Starcraft, you build your production facilites, and now you buy your units. These units fufill a specific role and it is up to the player to invest into the right combination of vehicles at the right time and make them cost effective. The team that makes better use of their investments will probably win. I say probably because there is more than just eco-management skill, but being cost-effective sure does help.
Earning your keep
Kinda based off from the previous point, but noticable. Unlike a game like battlefield where you have 3 people camping the jet, in Starhawk you need to earn your stuff. You don't have to fight over a Jet. If you want a HAwk, you can get one. But you need to be active, you need to do something and get Rift. This lets a team be more productive when you're playing with randoms or people who like to lone-wolf it. This also makes sure that those who are good pilots and want to get a Hawk will eventually get one, and can continue getting them if they have success in the air. They don't have to deal with a weird skew of Warhawk spawns depending on the base. Like Archipelago's 4 warhawks for the middle alone, but only 3 for the other 2 bases. Now this wasn't a huge problem in other maps since many levels made them plentiful(which was a reason for their over-dominance), however some maps, it made getting a Warhawk tight buisness...especially if you didn't have the right base.
Waste not, spawn mined not
This is a not so obvious but potentially important aspect of it as well. Now, on some levels like Island Outpost, you'd have so many Warhawk spawns you can recycle that metal and make a skyscraper with them. My point being that there were usually leftovers that just sat there. Now that you have to buy your hawks, they will only appear for those that want them. How is this significant? Well aside from not having to deal with the ole' mines below your Warhawk spawn, the more problematic thing were dropships. They were only as good as the Warhawks around it. If you did indeed manage to get air dominance, dropships massacred anything on the ground with greater efficiancy than even Warhawks. However, if you didn't have that dominace your dropship was worthless, and if your getting baseraped you won't be touching that thing....but the enemy team might like to borrow it. Since you didn't have the option to prevent it from spawning you had two options. A) Babysit it and and make sure they didn't take it or B) Let them take it, have 2 dropships, and turn a base rape into a base genocide.
The tank is another example, no expansion needed. It was common to fly, or take a jeep to a base that wasn't exactly a hotspot and steal a tank that was there to capture the base and then leave. Since you only get what vehicles you buy, there won't be anything that will only sit there to collect dust or be used against you.
These are just some theories, and I may be(probably) wrong. Then again, we'll get an Idea when the beta hits.