Okay. Here goes:
1. Yes. Speakers are the most important component in our systems.
2. No. New materials are always being developed; lighter materials for cones, stronger magnets, etc.
3.,4.,5. Possibly. Electrostats may improve like any other technology, but there does not seem to be a whole lot of interest in this technology. Reducing size seems even more unlikely, as the panel vibrates so minutely that the only way to get bass volume would require large panels. Cost would be dictated by its market acceptance. Large panels in the living room have low WAF, so lower prices are unlikely.
6. The "new tech ribbons" if they exist have the best chance of succeeding if they can be efficient, but only when used with dynamic cones. Read my earlier post.
I think the bigger issue with regard to speaker design breakthroughs is that our best and brightest minds are not working on them. The suckout is probably due to computer technology and all its relatives. And also, the relative lack of profit potential, both on sole proprieter and big business levels. Think about it, over that last 18 years (the length of time I've been involved in audio) has there really been any major breakthroughs? Back then, there were some systems (all analog) that provided as much or even more emotional impact than any system I've heard today, even though it may not have been as refined or transparent.