1. Somewhat likely.
2. Not likely at all. The 3G version sold very poorly. For all we know, AT&T still has exclusivity.
Also, LTE isn't available in all countries, which is why they did 3G in the first place (so you could have the same hardware internals globally)
Also, LTE is a huge battery sucker. The Galaxy Nexus HSPA+ version has 9 hours battery life. The LTE version has 5.
Now imagine cutting into the 3-5 hour battery life on the Vita with LTE power consumption.
Not to mention it's a slap in the face to the people who bought the 3G version. "Oh, thanks for buying the skimped version, here's the 'full version' of that kind of feature".
They're not gonna make a 4G LTE model.