I'm more worried now that they're going to completely overhaul Healers.

I'm worried because SE doesn't exactly have the best track record when it comes to reworking jobs (Bowmage anyone?) and we all know they don't do player testing.

So we're essentially going to Beta test healers once ShB drops. Why am I confident in saying this?

Because when SB was shown, all the healers raised concerns about WHM Lilies and SCH MP costs and lack of AoE. Nothing changed and both were released and criticisms were shown to be right.