It is still on list of patterns but, like you wrote hasn't been used for a couple years

http://www.pba.com/OilPatterns/Pattern/3

Shark largely became redundant when they lengthened the other patterns, plus added the Badger.  Shark was at one time the longest at 45 feet.  Now the Scorpion is 47, the Chameleon is close to 45, and the Badger is 52. 

I think the progression to longer patterns is the best thing they have done.  It has forced the players to learn more finesse because it is no longer possible to over power the patterns ( at least fresh ) with revs and axis rotation.   Learning to roll the ball, control your speed, and take advantage of hold area had become a lost art.   

Actually on wood lanes we looked for the area that would open up first.  35 to 40 feet of oil on wood played pretty tight with rubber and plastic balls.  The fall back shots guys played on the Scorpion was pretty common on lacquer finished wood.

Learned the game on lacquer.  Track developed between 10 and 15 board pretty quickly.  We didn't have to point at the head pin.  Lot of fall back at 4th arrow on lacquer, but you needed a good roll pattern to carry.  There were a lot of corner shots built in by lane men on lacquer but I never got good off the corner till lacquer was on the way out.  We didn't hook the ball like they did on short oil, or like the boomers can today, but we hooked it, and ability to throw a heavy rolling hook that could carry was what separated the elite from a lot of accurate guys who couldn't do it.

Something we knew back then that guys are starting to learn again is that amount of hook is less important than the roll pattern and revs on the ball when it comes to carry. During the short oil era of the 80's this was forgotten, because it was impossible to throw a strong release that didn't hook a bunch.  Not so much on the long patterns.