If the Ebacc means that schools drop everything else except the core subjects to concentrate on getting as many children as possible through the Ebacc, then yes, that is bad news for all non-core subjects, whether art, drama, RE, DT etc.
And given recent history with Sats and so on, there is a strong possibility that schools will do precisely that, as no doubt Ebacc scores will be what league tables and Ofsted judgements are based on. But I don't think that means that everyone should be forced to do an arty or practical subject as part of the Ebacc.
DS is 14 and is doing 10 GCSEs. He will probably get As/A*s in all of them. If he had to do art or DT he would be lucky to scrape a C - he is mildly dyspraxic, hated art and DT, and gave them up as soon as possible. They are also completely irrelevant to anything he would ever do in future. I would have hated being forced to do art, music or drama too - I have 10 O-levels, not including any of those subjects, but I help run an art museum, and go to concerts and theatres.
Most people I know who ended up working as actors didn't do any formal drama qualifications at school, and none of the musicians did music O-level - they were too busy doing grades in various instruments and music theory, and getting involved in local orchestras.
I thought the point of Ebacc (if it really has one - I think it's another one of Gove's ideas that hasn't been at all thought through) was to get all children to do a handful of core subjects which are essential for modern life and any further study? So obviously Maths and English, I would say also science, and after that it becomes debatable. It really doesn't help if every subject group now starts lobbying not to be left out - you'll end up with 10 compulsory subjects for everyone, and no flexibility to cater for individual strengths and interests.