Yes but this is linked to liquidity. The supply is linked to how many there are in circulation. This number keeps increasing.
The liquidity is how much is actually available to trade because people are willing to exchange them.
And yes I believe that mining cost is a floor price for Bitcoin. Being so close to that actual bottom I agree with you that the halving will increase the mining cost and also increase the price on the secondary market so to say.
I doubt that any of us really disagree about a variety of these points, and even though supply and liquidity are two different concepts, they are linked, as well.
By the way, I doubt that any of us, including you, have meaningful data to back up or quantify the extent to which: "this number keeps increasing." Yes, with the mining of bitcoins, every 10 minutes there are more bitcoins that are in circulation; however, there are all kinds of folks (and institutions) trying to measure the extent to which more bitcoins are being removed from circulation, merely because a certain number of folks would prefer to completely remove them from circulation by a method endearingly named as cold "HODLing."
I doubt that any of us are going to put it past BIG finance and even exchanges to attempt to rehypothicate or fractional reserve BTC to the extent that they are able to get away with it - nonetheless, it also seems that some of the January 3 celebration to promote the removal of coins from exchanges was to attempt to inbred a kind of bitcoin consiousness that distinguishes bitcoin from any previous asset (or money) that has been known to man (to date) and that is to claim possession of your coins, which can also become a very powerful tool to put any third party into check in the event that the extent of their rehypothication or fractional reserves is drawn into question.
I think that in sum, I am still saying, here, that HODLers of bitcoin still do not have great bitcoin auditing tools beyond just claiming your bitcoins and putting them into a private wallet. Furthermore, I don't think we have great tools to measure the extent to which a variety of people are exercising those cold HODLing practices in order to either safeguard their coins or to take a long term speculative bet that their bitcoins will be worth much more in the future, and there is some value in really removing them from circulation.