That is probably the wrong way to think about it. Its like saying "Well, we shouldnt be using motor cars because thats puts Horse carriages out of business". Or something to that effect.

We are moving towards a world where js is ubiquitous. Its everywhere..already. If web-crawlers dont support js completely ( looking at you google! ) then we should force them to (by creating more js based apps thats outside the crawlability of google ). If screen readers dont read js ( they should and thats why we have ARIA ), they will eventually. At the end of the day, as long as you are trying to adapt to them ( which is backward ) they will never move. Start moving swiftly and they will have to adapt to you.