Linear courses Watch
However, AS exams still exist so you could still take the AS at the end of Year 12 and stop there. The change is that if you do take AS exams in Y12 they will not count towards your final A level grade - they are decided purely by the A level exams (plus any coursework) at the end of Year 13.
As Compost says, there are AS options for the new reformed A levels and what you may be able to take and may be able to drop at the end of year 12 depends on the strategy adopted by your school or college. Different schools have taken different approaches to the new A levels.