While I would love the thought of a new 321. I caution that thinking.
The demand of the Speedmaster is derived heavily because of its history (horological and NASA). Adding the 321 back even in a limited form can dilute the brand and the vintage watch itself.
You may think Omega doesn't care about the vintage market (supply and demand aspect and how it effect modern pieces); however, they are definitely keeping taps. I highly doubt with the rise in vintage pieces would they try to dilute that. The vintage 321s are going to continue rise and I think Omega needs a watch they can point to in terms of vintage success. They need to justify/persuade those buying the new 1861 and most modern pieces of theirs.
Can you imagine if the remade the Paul Newman... I don't think that would fair well with Rolex collectors.
The only way I can see a 321 made in limited quantity if they had whole unused movements from the 60s and they made a brand new watch out of it.
EDIT:
I think it is important for a brand to move forward while honouring the past and heritage. Not to literally remake the past.
Omega is honouring the brand and moving forward: witness the calibre 9300 Speedmasters, including the 44mm modern moonwatch chronograph, the CK2915 and 2998 9300 calibre tributes, and the ceramic Speedmasters.
At the same time, the classic unadulterated Speedmaster Professional remains in production as a third-generation link to the past. Omega's corporate plan, as stated by their CEO who developed it, is to transition entirely to advanced in-house coaxial movements, with one exception: the classic handwound movement in the Speedmaster Professional moonwatch. I would venture a guess that there is a good business case for this, as there are probably a non-trivial number of first-time buyers who are drawn to the Omega brand by the moon watch itself. I know I was - and eventually, I bought a total of three Planet Oceans after my first Speedmaster Professional purchase!
Back to point; as long as Omega is going through the effort to maintain one handwound movement in its lineup, principally for heritage reasons, I think it would make sense to go all the way, do it properly, and sell the very movement that went to the moon, and was flight-qualified by NASA for all manned space missions.
With respect to diluting the value of vintage pieces, I think we have strong counterexamples that this would NOT be the case: look at vintage Rolex. There are many, many examples of 15xx-calibre movements, which were in production from around 1957 through 1990!! Yet the price of a vintage Submariner 5513 can vary anywhere from $5000 for a 1984-1990 model, to $12,000 for a 1967 model, to $30,000+ for a 1966 model! The value is entirely in the dial. A pointy crown guard 1963 5512 Submariner that fetches $35k literally sold this summer for $6200 FROM A DEALER because the otherwise correct watch had a service dial. So the value is in the original dial, and barely influenced by the movement. My point here is that new production calibre 321 movements would not diminish the value of vintage Speedmasters: in fact, they would engance the value of both the vintage market and the Omega brand. It would provide a path to sustainability and maintainability for collectors of the vintage pieces, while showing all customers, even prospective first time buyers, that Omega is committed to the long-term serviceability of their timepiece. That if they bought an Omega watch new today, they can rest assured that they will be able to properly maintain their watch over the long term.
This, in adddition to truly honoring the heritage of the Speedmaster Professional moonwatch.
