A completely different thought occurred to me about this abrogation claim. In case this has any merit, let me document my thoughts here. The point came up because of verse 4:18
which uses the same wording about death approaching, in the context of repentance. It occurred to me that the reason repentance is not accepted in this case is because "there is nothing to lose" whereas repentance while there is still a stretch of life entails certain behavior afterwards. By the same token, while one is free to give away his money any way one wants while one is alive, verse 2:180 in fact prohibits that when death approaches. The rationale in this case is that giving away your money earlier may not be taken lightly by you because it has consequences (you may run out of money in the remainder of your life, people who get the money may prove ungrateful to you, etc.), but there is nothing to lose if the money is given away when death approaches, hence the restriction on that in verse 2:180 is needed.
If this logic stands, then 2:180 is certainly not abrogated as it deals with a subject matter that is not touched upon in the inheritance verses. This is perhaps the reason why "يوصيكم" in the inheritance verses is done by God since the person is already deceased, while in 2:180 "الوصية" is by the person who is still alive. It also squares with the narration about the sahabi who wanted to give away his money to charity while on his death bed.