So we all know the major drawbacks of using chidori with out sharingan. It give you a tunnel vision effect that makes it possible to counter attack. But i think that if you become skilled and used to moving at such speeds it is ok. Take raikage for example he moves at a level much faster than kakashi and he seems to do just fine. Of course he can be counter attacked by someone using sharingan. Than we have kakashi who uses the lighting blade and other variants of chidori but i dont see why he needs sharingan. Look at rock lee and gai both extremely faster but skilled enough to deal with those speeds. Plus kakashi is not young and reckless he wont charge in on 20enemies take out 19 and give the last one a chance to counter attack. He got kakazu from behind he stood faced to face with pain and tried to attack him. He stopped zabuza's movements. So my opinion is basically kakashi can use his signature technique even now. Though he lost kamui which takes away from his power he still is basically the same kakashi