What will Prog be like in 2035?

 +  ... [serious technical face]

Judging by the speed in which technology advances and how slow markets are to react I suspect that in 20 years the music industry will have caught-up with the state of technology that we currently have. They will continue to make money and the Madonna's of that world will continue to be millionaires, the exponential earnings differential will still exist and 20% of the artists will still earn 95% of the sales revenue from music. Prog will remain a niche market and earnings will remain low for all Prog artists.

CDRs and the technology that we currently use for playing and burning our own CDs etc., will be as obsolete as the floppy disc is today, along with all of the interface standards that we currently rely on (for example USB will be as obsolete as RS232 or PCMCIA has been for the past 20 years). Computer memory will be entirely cache-memory with no capability for long-term storage. Internal and external hard-drives will not exist. The concept of files will be obsolete - everything will be a data-stream that will be accessed from the cloud, this will render the idea of any person owning data as a thing of the past. Everything will be streamed and once uploaded it will become the property of the service provider. Downloads will be obsolete as there will be no where to save them to.

All music will be streamed from subscription services run and operated by the major media corporation ... or MicroApplesoftSony as it will probably be known. This will possibly be a two-tier operation with 'signed' artists commanding a premium-rate streaming (pay-per-listen) and 'unsigned' artists at lower cost streaming (this could even be a pay-to-play subscription service to the artists until they exceed a prescribed number of streams per track). As with today - 'signed' artists will have their recording costs covered by the corporation, the 'unsigned' artists will be self-financed - the only difference will be that being 'signed' will be an automatic process that switches in (and out) once a fixed number of streams has been achieved. [They probably won't use the terms 'signed' and 'unsigned' but something equivalent]. 

But - prog will be different then in the sense that the people interested will be us (I'll be retiring around that time), and a bunch of younger people who are now learning to play musical instruments and listening to the likes of Opeth, Motorpsycho, Seven Impale, Steven Wilson and perhaps some of the RIO/Avant that appears now, like Ut Gret. That will be blended in with classic rock and original prog, following in the steps of the (by then 54 year old) Peter Jones of Tiger Moth Tales. 

I expect that electronics and perhaps even the dance music of modern day DJs may be included in a way I cannot predict right now - but to a lesser extend than what people learn now from listening to aforementioned bands, and The Flower Kings, Marillion, Genesis, Yes, King Crimson and Pink Floyd. The big names will always be major influences, that won't change much over 20 years unless a new musical revolution occurs.

So, more of the intricate melodic works we see now, with new influences and technology added if new musicians indeed decide do look forward instead of into the past.

The amount of 'old guys' playing and touring will likely be smaller though, because although the amount of bands and releases is massive, I see a lot of new albums being released by musicians in their 40s and sometimes even 50s who decided to release something after spending years in a 'regular day job'. They'll have slightly different careers over the next 20 years than say Steve Hackett and Rick Wakeman had over the past 40. 

As far as vocals are concerned, I tend to agree with you - many bands that started with grunts and growls have switched to melodic vocals, and the extreme metal genre will be a lot smaller in 20 years.

Artists that I hope will still be around to take over the roles of the the dinosaurs (Hackett, Howe, Waters, etc) and mammoths (Stolt, Gildenlöw, Trewavas etc) would be amongst others Franck Carducci, Peter Jones, and Unreal City's Emanuele Tarasconi.

Just the thought of Dolly and Jon's respective lyrical themes clashing is....erm..