Not sure if you guys are aware but, and you may want to sit down for this as it will shock ........... but the sport existed before Rossi, and it existed quite well in terms of supporter numbers and sponsorship dollars (actually had more bikes, riders and sponsors)
Yes, surely when he goes there will be an initial drop in viewership and the subsequent loss of dollars to DORNA but it will be nowhere near the 70% and you will find that relatively quickly the dollars will return to near or perhaps even exceed those attracted to Rossi.
With this I suspect that you will actually see supporters of the sport who had left during the formula Rossi years (where these people believed that there was an unfair allocation of resources) may return and there will be new supporters bought by new riders, sponsors or teams.
Rossi is not the sport despite what many wish to think and whilst he is influential in some eyes, to many people who were here (followers of the sport) before Rossi, we have seen how strong the sport can be without him, and so we have little to no long term fears.
When Rossi goes, I suspect that many forums will pass into oblivion as they will no longer have a primary focus for their posts but this place will survive
