This is valid.
I agree.
I will say the evidence of waning antibodies makes for a good news story but don't put too much stock in that for the moment. Until we see people getting reinfected, the finding of waning antibody might not be as significant as you think, at least not in the 6 month revaccination range. The immune system has a tendency to be reactivated with new exposures to the same virus.
For example, antibodies to the hepatitis B vaccine wane with time but immunity does not correlate with detectable circulating antibody. As long as there was documented immunity from the vaccine at some point, undetectable antibody, even at the time of an exposure, does not require a booster. The virus will stimulate the immune response.
The news media loves fear mongering.
This is a valid observation.
If we have a short lived vaccine there will be a number of variables at play.
First, if we eliminate the burden of the pathogen in large areas, it gives time for revaccinating, especially if rapid recognition of outbreaks and contact tracing is in place (ah the good old days when we had a functioning public health agency).
The drawback is there won't be a lot of natural boosting when a vaccinated person is exposed to the virus in the wild, naturally boosting the person's immunity. There is a bit of work going on now looking to see if lack of natural boosting to chicken pox (whether the initial immunity is from vaccine or natural disease) might contribute to an increase in shingles. You don't catch a new case of chicken pox if your immunity wanes, rather the latent virus in the person is reactivated.
Right now, the biggest problem we are facing was reiterated by the WHO today. Only a small fraction of the world's population has been infected so far. The pool of susceptible hosts is HUGE!
People who think this is over are really being misled by Trump and his fantasyland munchkins.