The x3d has been out for some time. It is now on v4 firmware. There will always be issues with any firmware. Many of the remaining issues are long standing related to the SDK. Realtek have stopped fixing issues in it as they have moved on to new chips. That leaves ingenuity to patch in fixes, and the results do not get to users unless they show some improvement.
Feature wise, I am not aware of any "big" feature in the pipeline. The box is already crambed full of features that wernt in V1 firmware.
Normally we would have had a new realtek chip which would be a evolution of what went before, thus allowing code to be ported with relative ease. All chips makers have gone down the ARM route , and that is more a revolution. It means the chips themselves have to be assessed as suitable platforms, and Sanji can't do what they want to do with any of them, especially at current prices. So there is lot of activity going on that users can't see.
Sanji will not make a new player for its own sake. I have been pointing out that current ARM player prices will bankrupt some well meaning companies trying to keep loyal customers happy. The x3d is still holding its own despite its age, and higher price.
Personally, I wish realtek would just produce an 1187.....a 4k bluray supporting version of the 1186 that allows code to be ported.