There is an answer to the other religions have survived argument.
Other religions don't rely so much on preaching to gain numbers. There is a superchurning inside the JW's. More and more hours are needed to gain members with US and UK numbers possibly already falling.
Second they have and do heavily rely on US and UK rich countries for the main flow of money. I just don't see too many ways out for them at this point. Are they going to start doing daycare and celebrating Christmas? If you look at pew survey it says most of these religions are surviving or
growing because they are dramatically adapting. I just don't see too much room for JW's to adapt.