Really? I mean come on, the German military had pretty much given up on the technology and the 1930's version had to be heavily subsidized to make it remotely profitable. I really think it was a stunt that the Germans ITTL wouldn't bother with, especially because they actually can make airplanes ITTL instead of having restrictions like Versailles. Also military advances in aeroplane technology would boost German civilian aviation that much more, making it even less likely that airships would be invested in.
Yes, really. I did not say the Zeppelin would be better than the airplane, but that the Airplane takes longer to replace the Zeppelin.
With a German victory, the Germany and the Zeppelin company are in much better financial shape. Once the war ends, the Zeppelin company will again focus on commercial markets. I can see a lot more than two passenger Zeppelins in the 1930's. I can see them being used into the 1950's on limited routes and even being used today on some tourist routes. A Zeppelin could provide a wonder experience on something like the Inner passage of Alaska, the Grand Canyon, etc. Do you believe in a Germany win scenario that only two post war passenger Zeppelins would be built, and they would have an operating life of only a few years? I can't see that scenario, and I would be interested on how you see the scenario unfolding. And how/why Germany scraps the Zeppelins after the war instead of continued naval usage or civilian commercial usage.
Now what you say is true if you look at it from the Army perspective. By very early 1915, it was clear Zeppelins could not be used against fortress like Liege or Verdun to any real effect, and airplanes were used. In 1915, it is clear they are not a good interdiction tool against items like railroad bridges. By 1916/1917, regular bombers are beginning to replace them on strategic bombing of Paris and London. So yes, they are not a land based weapon, and were a waste of resources for the Germans except the British wasted even more resources defending against them.
The naval picture is different. They were very useful, and I believed they were used until the very end of the war successfully. They went out with the High Seas Fleet at Jutland, and with better weather conditions for the Zeppelins would have been a major help. On a clearer day, they give the High Seas fleet several hours to half a day warning on the approach of the main body of the Grand Fleet, and would have give the VizeAdmiral a chance to either deploy in a more favorable tactical situation or safely retreat to port. On clear weather days (admittedly, under half the time), the Zeppelins made it very difficult to approach the German bases with large forces undetected. Not impossible, but harder. Zeppelin steered the U-boat to the "Live bait" squadron. I see no reason in a German win with the ship already built, that they would just be all scrapped by the mid 1920's. When radar is invented, the become even better warning system. And Zeppelins were cheap in men and material compared to even a single light cruiser.
IOTL, Pearl Harbor probably is not attacked if the USA has radar capable Zeppelins. Even with just visual Zeppelins, the Japanese would likely have rethought the attack. Zeppelins would have been useful protecting American Coastal waters in 1942 from U-boats. A Zeppelin with radar gives the Prince of Wales an hour warning on the approaching the Japanese Planes, and could have been 50-100 mile south of the PoW. A Zeppelin would be good in a role such as finding the Bismark.
Zeppelin are not a magic bullet, but like PT boats and scout planes, are very useful in certain situations. If you have a source where the Germans had decided to abandon using naval Zeppelins before the war ended, I would be interested. The fact that they were on the banned weapon lists, not limited weapon list, indicates that either the French or British thought they were still useful weapons in 1919.
As to the German military giving up on the technology, I show that to be late in the very late 1930's, and Germany had no real navy to speak of, so there was no need for a naval Zeppelin. As to the subsidies, there is often an economies of scale, and likely not having the interruption in usage means they scale is large enough to make practical. It would be like modern dual use technology, the military pays the capital costs, and the private sector is paying close to marginal costs. With the High Seas Fleet still in existence,and possible major overseas Naval base (lot depends on POD), i don't see why the Germans abandon a useful tool as quick as OTL.