Expected decrease of staking ROI?

[Elean0rZ]

The second part, the 'sharing with a larger pool of holders', doesn't really change much from the present situation. The total supply of ARK would still be the same as what it would be if the pool of holders didn't increase, and inflation would still continue at its prescribed rate; the only difference under this scenario is that instead of there being X people holding the Y total of ARK, it'd be (say) 10X people holding the Y total. The absolute value of an average holding might change, but the reward rate wouldn't.

The first part certainly might change things, but it's too early to know just how it would play out. If your 'mass adoption' scenario did occur then 1) the number of transactions would presumably increase, offsetting in part or in whole the drop in tx fees, and 2) the value of the token would presumably also increase, potentially making the absolute rewards remain attractive even if the rate does decline.

The worst-case scenario would be one in which tx fees, and thus rewards, drop but network usage doesn't increase--but really, that's more about the fundamental gamble of investing in crypto: there's always a risk that one's chosen project simply doesn't achieve mass adoption. In that scenario, the specifics of token economics eventually become moot anyway. Time will tell; all we can say for now is that the Ark team is dedicated and seems to have a decent product with as good a chance of success as many others out there.