If Sony changes anything, they will only allow in-spec burned non-watermarked discs, you know, the kind that consumers would be making for their own content, or maybe small-run commercial discs.
They will never allow SACD-Rs.
The current feature-set is perfectly reasonable. In the major countries where Sony operates, nobody at home is really using DVD-A, and those that do have an overwhelming amount of pressed commercial titles over burned commercial titles. In these major countries, making backups of your owned content ranges from a legal grey area to downright illegal and in Sony's home country, can get you real-world jail time. If we eliminate the backup and piracy buckets, we aren't left with anybody really who needs DVD-R based DVD-A playback. It's rare that DVD-A discs contain anything that extensively uses the format's capabilities, and people making multichannel music, due to the lack of authoring tools, would either be doing a normal DVD or jumping straight to Blu-ray, where the two largest support bases lie. Also, in the internet age, more people are using FLAC files than discs, which can be easily loaded off a USB.
The X800 series are for those who own enough physical media to warrant a universal player. The X800 series does almost everything you need for commercial and user-created media. It's fine to ask for DVD-R DVD-A support, I have no problem against that. However, I think it's a bit silly to bash Sony extensively for not supporting a feature that very few people are going to legitimately use, regardless of whether the restrictions may be arbitrary or not. Those who are wanting to use backups to preserve their discs would usually not be using discs.
Just my two cents...FWIW.