I think it is an interesting question. For me there are two scenarios:

1) temporary demographic blip

Alot of guys who were 10-15 years old in the 60-70s and liked motorsport have a connection with Heuer. These guys now have excess cash to spend on a few toys. Once this generation gets older there is no "natural" value to Heuer (compared to the more established swiss manufcts) and the interest will disappate and values will be destroyed.

2) permanent rises

the natural interest in Heuers is maintained, plus LVMH pump the past and raise the image of he TAG-Heuer brand above "midmarket". Vintage Heuers get rarer and rarer and finally a very rare "black faced Siefert" model Autavia with a TAG Fomula 1 bezel sells for $10,000 on ebay in 2008. Later that year, OTD aquires AOL. Well, you get the point anyway.

Not so obvious which of these will happen. Probably most likely prices restabilise and dont change much.

Not sure how much to blame Jeff & OTD. The interest was obviously there, just waiting to be shown the true way.