I don't think that it is over - but it does seem to be under increasing pressure in terms of spectator behaviour and the numbers attending versus the supporting infrastructure (or lack of it).
The circuit changes have been made for various reasons, and the supporting facilities do seem to improve year on year, even if some of the character is lost in the process. Amd that is where the corporate stuff comes in. In the years that I've been going, the grandstands have got better, the number of pits (and grid size) has increased, the old view back up the track from the Indianapolis corner was restored this year with the removal of the screening (hurrah), the Tetre Rouge bank is now a great place to watch from and, yes, I do really miss thing like the fair (where/how it was) and the straight run down from the Dunlop Bridge to the Esses, viewed from outside the circuit in line with the track at dusk or dawn. The campsite facilities are getting better - I remember two porcelain footprint traps and a couple of pig troughs that comprised the Houx ablutions at one point, and I certainly don't wish for them to return!
In terms of the spectator behaviour, there are a lot more people attending now, so given that the various activities happen roughly in the same place/time from year to year, any "bad" element is likely to stand out more now in any given situation or place, given the increase ni numbers and the desire to "outdo" each other. I mean, Arnage used to be a good load of simple fun - a bit of wheelspinning, promendaing, a good-natured crowd and the odd bit of chucking water around. Then came more water and water pistols. Then improved "contents", including beer and p*iss thrown from jugs etc etc.
This year, we didn't really see much of any of that, because we simply decided to avoid it and find other things to do - Friday was a brilliant day - got the supermarket shopping in, drove down the Mulsanne (lots of nice cars and good-natured crowds parked up near Hunaudieres), followed by the Classic British Welcome, CA Cavalcade and the DfH party. Simply went nowhere near HA roundabout, the drag strip in front of Bleu, Arnage, the town centre, or anywhere else like that. End result was a great day out and about, with a bundle of nice people, doing something different.
All in all, I think that the Golden Era is still there - it just takes more to find it and, in some ways, we have to make some of it happen too.
MG Mark