Two calculators will be bought.
Students will buy a graphics, because it is far superior to a pocket calculator for most Engineering problems and if they do not own or buy math software for a PC or laptop.
In their Senior year, when they discover that their precious graphics calculator cannot be used, they will buy a pocket calculator. A wise student may have already bought the Hp9G (one of the few graphics specifically allowed on the exam), but most will assume it to be RPN, it isn't. Most engineering students today do not use RPN. Sad, but true. Most stay with the Ti they purchased in High school. And this is their tool until it is stolen, breaks down, or doesn't have the horsepower needed ie Ti-83 for an EE would be replaced as a sophomore or junior. But most Ti users will stay Ti users.
Yes the 33s will sell well, but only because it has no competetion in the Pocket calculator market. If Ti were to release a clone Hp27s without IR (ie Ti-68 with 8+ K RAM and four letter variables, it would stomp on an Hp33s in the market place.