Oricon vs. Billboard

[Max_ZZZ]

Honestly...

I've been following Ayu's single streak (since the album one is gone lol) and I've been so excited that she has such a good chance!

But I've been thinking...
Billboard (the US charts) is sooo accurate because it constantly changes to accomadate the changes of what determines how popular a song is. So now they include digital downloads and less for physical single sales. But...
Oricon is still solely based on physical sales. In fact, it doesn't look like it'll change. So obviously all these rankings are slightly flawed right?

So if suddenly they decide it's not accurate anymore and more to a more reliable chart or whatnot... what happens to all these records? Especially ayus LOL like... does any one know what I mean?

What happens from here on? Is still following solely physical sales enough?