That is a matter of opinion. Most people just a want a vintage steel bike to remind them of the bike they had "back then", some like a lot of people here want a vintage bike because we prefer the ride of steel over carbon and have several because we like the way different bikes feel when riding them. If that makes the collectable then I guess they are.

They are not collectable in the same sense as a coin or a painting where if you a buy a bike today for $500 you could likely sell it for 700 or 800 or more in a few years.

Some bikes like Colnago, De Rosa, Merckxx and Bianchi are sought after because of the ride quality and craftsmanship in building the bikes. But again whether they can be considered collectables is a big debate.

I like the look of that Panasonic and would be something I might buy to try out, I don't think I would pay much over $200 to 250ish for it. judging by the grease and dirt on the chain, crank and rear derailleur this thing needs a lot of cleaning, not to mention a complete overhaul. I also suspect the chain is excessively stretched out and very likely has worn the freewheel (FW) cogs as well. So between those two things I am looking at $100 worth of my time for labor and #-50 for a chain and FW and who knows what other parts.