We just have to wait and see, but if the technique has been labelled a forbidden uchiha technique that clearly hints that uchiha's in the past have used it and its now forbidden, which hints that true uchiha's dont need senju dna
well we have to remember anything tobi says could easily be a lie unless also said by someone else, so anything he says should be taken with a grain of salt. Also i think the major reason for tobi and danzo needing senju dna to use those techs was more because of the sheer volume, not necessarily them not being uchiha. Danzo needed the boosted life force because he was using what, a dozen? So using a powerful move like that, that many times would probably drain him to death normally. As for tobi, i bet its similar, whether his powers are izanagi or some other unknown sharingan tech, as much as he spams it in battle to not get hit means a huge drain on chakra. If all his stuff is simply S/T and not sharingan related my best guess is that he needed senju dna to heal after that pwning minato dealt him. I say all this because while the uchihas can use it just fine, remember they only have 2 eyes to use it with, so even the typically low chakra/stamina level of the average uchiha can probably survive 2 uses of izanagi, but i bet without it if sasuke had a dozen put in his arm like danzo, i bet he would drop from spamming them without senju dna.
