Exorbitant is in the eyes of the consumer. If people will buy $300 video cards, then nVidia, Matrox, ATI will try to sell $300 cards. Personally my threshold is about $100-$125, so I'm more of a cheapie than the rest of this BBS. I can't picture spending $200 on a card simply to play games. I'm willing to simply play them at a lower resolution until the card drops down below $100.
There's still plenty of competition. If ATI and Matrox fold, then we can start worrying about a lack of competition in the video card space. S3 leaving was a bit of a concern, 3Dfx dissolving is worrying. If ATI and Matrox leave the picture, then we can start to really be concerned.
If prices really start to skyrocket and technology starts stagnate due to a lack of competition, then someone else will step in. If margins are high, this creates a "vacuum" and into this vacuum someone else will step. It may take a year or two for them to show up, but someone else will show up. The nice thing about video chipsets is that the threshold of entry is not ridiculously high (like, for example, CPU's and hard drives). You can gather venture capital, license off a bunch of software from Synopsys and Cadence, put together a team of engineers by promising an IPO, and create a video chipset from scratch in a couple of years and then have someone in Taiwan fab it for you. 3Dfx and nVidia were nothing 5 years ago. S3 ruled the world. Before that it was Trident. Before that Hercules. Companies fold and new companies take their place bringing new innovation. This, to me, is the sign of a vibrant industry.