"That" refers to the previous discussion just mentioned, and "now" confirms it by contrasting with 1 or 3.5 years ago. The point is that it is possible some of

"That" refers to the previous discussion just mentioned, and "now" confirms it by contrasting with 1 or 3.5 years ago. The point is that it is possible some of the criticisms and problems discussed back then could have been fixed since then (though I don't know, hence "may").