You actually can still use it, there’s some folks on reddit trying their best to keep it going. App support is very poor though.

AFAIK you can enable the snapcast server and then use an app like SnapCast to stream to your mobile devices.

The newer Sony Xperias sound like a good fit for you. I haven’t used one myself, but they’re pretty decent from what I can gather.

Also it seems as if Sony is the only phone manufacturer shipping flagships with headphone jacks and SD card slots.

On another note, I highly recommend the GSMarena Phone Finder for getting a general selection of phones that have the features you care about.