Interestingly the value of the best vintage watches has not been significantly impacted to date and the guide has remained mostly "as is" apart from a few gentle downward movements here and there, mostly on 1970 Autavia and 1960/70s Carrera. I would suggest that there continues to be a higher appetite for the best and rarest and then also for under £10k segment, where there are a lot of great Heuers priced at similar levels to what I loosely refer to as "modern rubbish" ;) When interpreting the guide I would caution that mint really does mean that, so watches with 95% unmarked dials, with matching condition hands/lume, and unadulterated cases with mint bezels and with all original parts. This is in reality a very small % of the market, certainly far less than the amount of sellers who refer to the watch they are selling as "mint"!
As posted on my Instagram account there are more and more "service" bezels appearing in the market, since TAG Heuer started to remanufacture them in 2017, the obvious tell is they have little or no serifs on the numerals/text (and on Rindts/Andrettis seem to be less glossy than the originals). They are of course worth substantially less than the original period ones, as they would be on UG, Rolex and Omega etc. It is quite a black and white matter, but I am aware of some people saying there is a grey area, I would suggest only if you are the one selling them ;) When buying vintage pieces continue to educate yourself, and don't believe what people tell you just as a matter of course. Sellers can have an agenda or to be more kind have a "jack of all brands" knowledge base because in reality it is impossible to be an expert on all brands.
Where the market will end up in another 6 months is anyones guess, but with the continuing likelihood of an even further extension of low bank rates (making cash in the bank stagnate) and general uncertainty in the financial markets I suspect desirable physical assets will continue to perform well. Add to this the fact that more and more people are interested in collecting watches, means it's unlikely (because many are under 40) that it will become unfashionable anytime soon. As always time will tell...
Note that this month sees all Heuer Skipper references appearing in the guide for the first time. It also features more values for previously unvalued models (XXXXX), where values taken from the past 3 years of auction results combined with private results have enabled guide values to now be realistic (especially now the market has settled). There are still some watches where "Demand Fulfilment" appears for the truly rare Heuer grails where insufficient data is available.