I don't think a lot of witnesses doubt the teachings. I lot of them I know, could be told "jesus has come back in the form of mel gibson" and they'd believe it simply b/c 'its from the faithful and discreet slave'. They don't really have good reasoning skills.
As for numbers (increasing/decreasing) I still think the org. would lose a lot of people. If the org. did allow members to look at websites, true it probably wouldn't be viewed as a cult but a change such as described would eventually turn the system into something completely different. They'd probably end of changing their name too.