I don't particularly like Minfilia, admittedly, but I only want her to be sacrificed if the 'big reveal' is going to involve telling us that mortals should not be sacrificing themselves in the name of divine entities/noble causes. It shouldn't really be something to aspire to. If Hydaelyn does indeed take over Minfilia or 'absorb' her somehow then how is that any different to what the Ascians do on behalf of Zodiark? To me that simply implies that both Hydaelyn and Zodiark are parasites exploiting mortals as willing or unwilling pawns in their ongoing feud. Even if one side is better than the other...it's still a case of mortals being exploited.
Obviously I'll wait and see how it's all handled. 3.2 does excite me quite a bit - and I'm hoping they deliver on the promise of a 'darker' expansion as we push towards the finale of the Dragonsong War.