I think that could be a little extreme, the hobby will always be around as there will always be people that love building and flying model aircraft. As the real aircraft become more exotic so will the models.
Unfortunately the odds are indeed stacked against the hobby in a lot of areas not just from the above points. The encroachment of housing near well-established flying fields are making waves, old local council empty blocks that were clubs for years and never had any interest to anyone are now worth $$ and the developers see the potential.
The total out of control quadcopter market has put a lot of pressure on the relevant authorities to try and tighten everything up and the back end will probably involve increasing insurance rates soon as well, and will probably put further puressure on fields and there locations. Threats from these stupid things are also making alot of issues and the authoities normally knee jerk laws regarding them quickly into action.
Same can be said for full scale airports whereas again the local authorities have sold off all the land around the runways so now you have houses 50 foot either side of the runways.
Yes the numbers will drop but I think there will still be the faithful, probably like most hobbies. If you look at build threads they are still going strong.

Regards,