I heard that the Pepsi Max Big one is going to be expanded for a much higher first drop and longer circuit.
No not possible. The only way they could do that would be to completely demolish the PMBO and start again from stratch with the spare peices from the big one etc. Increasing the height of PMBO would throw the physics off for the entire track, and the track isnt great at the best of times.
Also Real i wouldnt be to worried about being sand blasted whilst riding the coaster. As the 'sand' at Blackpool is more of a mixture of mud and sand. Its weird at Blackpool though. When the tide goes it, it goes out about 1/2 km. But when its in its crashing over the sea defenses onto the road. Bear in mind that the Pleasure Beach is only literaly across the road 20-30ft or so. So with the sea crashing up on the sea defenses and what not it kicks out a hell of alot of spray