Follow the excellent advice you have received here. You have a great camera and it will serve you well. You are just feeling buyer's remorse.
Worse case is Pentax goes belly up and the market is flooded with equipment. Your camera still works, buy a spare body for a song and keep taking pictures.
Now Hoya spent a small fortune to buy Pentax several years ago. They have had a successful string of camera models - K7, Kx, K5 and Kr. The 645D medium format camera at $9,000 +/- is selling very well. If anyone has a worry it would be a 645D user and they are confident in their new acquisitions.
I had to drive over to the other side of town this morning, and on the way back I stopped at a large electronics store. They had a wide assortment of cameras, and carried both the Pentax K7 and Kx. The small Pentax compared to the massive Canons, Nikons and Sonys stood out as an exception. Their lenses are enormous. Body and lens together need a wheelbarrow for transportation.
You have made an excellent choice. The pictures will be wonderful. There is a wealth of equipment / lenses available to meet just about anyone's need. 40 year old wonderful lenses will work just fine. Pentax is not going to go anywhere. They are a survivor, and are doing just fine - just look at their most recent releases.
Take pictures with confidence!