I’m slightly more worried about world memory overflow due to dropped tools, and especially left behind trimmings from felled trees. At least the tree process can be called X leaf dust, bark dust, etc on the block as described for other types of dirt.
Normal play is fine, especially as those tools keep all of their data wherever they are stored (including as free object on the ground). And, iirc, there was consideration of unloading boring chunks.
Having (a hook in) the block replace code check adjacent spaces it can export the dirt (or other replaceable block element) into would be no worse than a single-tick liquid source. Or for some porous blocks you could allow them to have the dust internally (like mortar in bricks).