She's been gone WAY too long for her to have massive sales.
I think she'll sell a bit over Platinum in the US and easily go multi-platinum in Canada, worldwide it really is a toss up. She used to be so huge globally in the COO and Up! eras globally but Iike I said she hasn't released a studio album in over 10 year so IDK.
Hopefully she does some worldwide promo as well, especially here in the UK where she used to be massive.