Sharknado was a strange success. It was so bad, people couldn't look away. If they use the same cheesy elements combined with the same bad special effects and similar acting and story line, I assume that Sharknado II will follow the same path as its predecessor. Nothing like a guilty pleasure time wasting movie.
Yes, SyFy's Sharknado II will be a success, because the show has very, very loyal fans. There are websites dedicated to Sharknado. There are people who discuss it in message boards. Usually sequels are not that popular, but with such a loyal fan base, they are all anticipating Sharnado II and its relayed hype.
Sharknado was the peak in SyFy's tendency to pick up on the cheesiest possible modern B-films - a film that combined the genre's recent obsession with killer sharks and disaster films. Sharknado was successful for a number of reasons, mostly its title, but rushing out a sequel is the sort of thing best left to the heartless Hollywood system.
Despite Sharknado hiring on some decent Hollywood talent I have my doubts it will be heard of outside of the SyFy network. I had never heard of Sharknado prior to this and I doubt I'll hear much about it, after this. Crappy sci-fi films only become prominent if they obtain a cult following, which is pretty rare.
Sharknado II is the sequel to a movie that should have never been a success in the first place. Sharknado was a well timed stumble into pop culture just for its shear ridiculousness. The novelty of the situation is lost. The idea that sharks are flying through the air was an instant rush that simply cannot be repeated. This is the same reason there has never been a "Snakes on a Plane II"