Re: The future here ...
Long ago I would have agreed that solid boosters did not "have an off switch". But they have to be turned off somehow in order to be put on the right trajectory for an ICBM, and those have been solid state for many years now! I finally realized, and clearly others already had, that if you just "open up" the front end then the thrust goes to zero. That is not a simple switch, but it serves the purpose.