As far as I'm aware from the developer chat, bootstrap will replace MyMobile - in what form I don't know. But it was said that it would replace it when it's ready which makes me wonder why the forums have already had jQuery / jQueryMobile taken out - hence the poor rendering. I had almost got a temporary good TinyMCE editor working for the posting in forum issue - this discussion. I was also working on a number of improvements with Mary Evans and had a YUI wrapper lined up (thanks to Andrew Nicols) to ring fence jQuery within core.
To be honest, looking to the future, what exactly will survive who knows. jQueryMobile my die, but then it is community supported. Yahoo may go into receivership - but looking at their stock levels, probably not. However with all the developments in mobiles, HTML5, embedded Java and the increase in true distrubuted technologies different things will be better and push developments in new directions.
My view is always to take the best of what is on offer, integrate it and provide the best user experience. As Frank Herbert once wrote 'fear is the mind killer'.