I can state that they have not.
I was in Japan in March - April of this year and 
Photon and Now And Then Here And There were 
dumped on the market while I was there.
these shows came out several years ago.
It can take up to 3-4 yearr for a show to get 
dumped, as many are bought by speculators(not 
really anymore due to the cel market collapse)
but many show are still being held by groups, 
and many are now being sold off so they can try 
and make some money.
I believe that there are still a few dozen large 
blocks of cels from shows out there including 
the few recent celed ones that still have not 
been dumped yet either.
Of course this is all my opinion as well,
so take it as you will