Apart from if this should happen, what is the thought process for choosing what to "de-extinct"? Marketability (large mammal vs tiny insect excites the populace more, leading to funding)? Viability (proximity to existing species genome means less work filling the gaps, quicker to market)? Biological disruption (some species easier to control than others)? Other?
Also, what geopolitical entity is willing to host the results? For example wooly mammoth might really appeal to tropical-based group, but must be hosted in sub-arctic region.
- Availability of genetic material (for extinct animals) can be widely variable. For something like mammoths, we've been able to extract genetic material from frozen arctic samples; one would have to assume that samples as large as mammoths are more likely to draw notice and researchers than, say, a preserved mosquito (Jurassic park notwithstanding).
- Proximity to existing species' reproductive biology: we know _a lot_ about how to manipulate reproductive processes in large placental mammals, and most of this sort of cloning is performed mechanically by harnessing the reproductive process of a host with similar biology (in this case presumably by implanting an embryo in a modern elephant for gestation).
Also, what geopolitical entity is willing to host the results? For example wooly mammoth might really appeal to tropical-based group, but must be hosted in sub-arctic region.