What happens to autism rates if we stop MMR?

From Honda et al 2005 J Child Psychol Psychiatry 46(6):572-9 (without permission):

"The Japanese MMR vaccination program targeted one-year-olds between April 1989 and April 1993, then was discontinued. Therefore, children born during the years 1988 to 1992 received the MMR vaccine in years 1989 to 1993 at one year of age. According to Yokohama statistics, MMR vaccination rates declined from 69.8% in the 1988 birth cohort, to 42.9%, 33.6%, 24.0%, and a mere 1.8% in birth cohorts 1989 to 1992...the seven-year cumulative incidence of ASD rose progressively from 47.6 per 10,000 for children born in 1988 to 117.2 for those born in 1996, that this rise continued in cohorts of children born after MMR was withdrawn, and that no decline in ASD incidence occurred in the five-year period from 1988 to 1992 during which MMR vaccine usage fell from 69.8% to zero population coverage...Accordingly, it is possible to conclude that it is extremely unlikely that MMR has been responsible for the rise over time in the incidence of diagnosed autism. It follows that it is similarly unlikely that it causes autism frequently or at all. It cannot have caused autism in the many children with ASD in Japan who were born and grew up in the era when MMR was not available. Because this frequency is at least as high as in populations in other countries in which most children were vaccinated, it implies that MMR could not cause a substantial proportion of cases of autism."

That is, when Japan stopped MMR its rates of autism kept on rising, which is not what we would expect if the rise in autism rates (if they are real rises and not due to changing diagnostic patterns, see below) were due to MMR.