I'm not sure I did understand you, but are you saying that 50 timecoins (or wathever the reward is) will be lost every 10 minutes on average?
If the number of coins lost in the average ten-minute period is generally increasing as the number of spendable coins increases (equivalent to a positive correlation between losses over any time period and the supply), then there is a number of spendable coins where the expectation of coins lost in the next ten minutes equals any positive constant you care to name.
If the rate is 0.00009% of spendable per block (which annualizes to about 0.5% per year, which I suspect is the right order-of-magnitude), then a reward of 50 TMC implies about 526 million TMC as the equilibrium supply; 2 TMC implies a 21 million supply at equilibrium. TimeCoin implemented as BitCoin with a 2 TMC minimum block reward would not fork until the BTC reward drops to 1.5625.
I think now I understand. The bigger the total supply, the more units will be lost (with each generated block). That's why the supply of timecoin would converge too: when the losses equal the rewards.
Well, if timecoin and freicoin will have a constant supply and bitcoin a decreasing supply, maybe it's more appropriate to define freicoin as timecoin with demurrage.
I was considering that bitcoin and freicoin will have constant supply and timecoin won't.
The constant block reward of freicoin could just be deduced from constant supply (in the end) and demurrage.
I was ignoring the effects of wallet losses in supply.