TN's are cheap to make compared with the other technologies. Advantages are quick reaction times and cheaper, since they're more resilient to manufacturing errors and particles so their yields are relatively high compared with the other types.
VA's (MVA, PVA, what have you) are basically TNs but in multiple directions. Rather than directing the light straight (perpendicular to the screen) like with TN, VA have different regions which direct the light toward different directions -- i.e. a region that points to the left, another that points to the right, etc. This increases the viewing angle but means the reaction time increases; also, since manufacturers apparently forgot to include a region that points straight up, this also means that when looking straight-on at the screen, the quality is somewhat less than looking at it slightly diagonally, since straight-on is not the primary direction of any region -- you're basically looking at a TN from say a 30 degree angle when you look at a VA head-on.
I'm not that familiar with IPS technology so got nothing to say about that
The future is probably going to go toward TN, but not only because of price -- it's also because TN quality is steadily improving. As TN quality improves, the average consumer is more going to notice the price differential between TN and other types rather than how much benefit the other types will bring; the cheaper price also means that more people can trend toward this technology compared with other technologies. Think of economy flying versus business or first class 50 years ago compared with today.