There was already a teshuvah passed a number of years ago by Rabbi Joel Roth, wherein he opined that individual women can be considered chayavot (obligated) for mitzvot asei shel hazman grama (positive timebound mitzvot) if they choose to consider themselves bound.
I should probably read this newer teshuvah, since I would want to know how they are phrasing the establishment of a blanket shift to all women being chayavot, since I think it would be very hard to find adequate halachic precedent for such a thing if framed as a regular responsum. You could do it by takkanah (halachic legislative injuction), but the movement has so far been reluctant to embrace the usage of takkanot, perhaps out of shame or embarrassment at the attempts in the 1950s to pass off certain poorly written "teshuvot" as takkanot.
I don't necessarily have a problem with creating a blanket obligation for all women to mitzvot asei shel hazman grama, I would just want it done in a halachically sound and defensible manner. And I confess I am skeptical about this new teshuvah. Not all our rabbis are as careful and painstaking as I might wish in composing their responsa; although of course that is true in every movement, not just ours-- even in Orthodox circles, there is no shortage of poorly executed teshuvot.
FWIW, I think the whole "what if she needed to nurse a breastfeeding child" thing is a red herring. Personally, I think breastfeeding should be permitted in shul. If she's in a position where it really would be difficult or improper to do so, such as if she were the rabbi or cantor leading services, then she could pump or supplement with formula, and make sure to have child care while she leads the service, and that person could feed/soothe the baby. Though neither of our kids breastfed, my wife would always make sure to have child care when she led services at her shul and brought the kids with her, same as I do when I bring them to my shul with me. And more often than not, we leave them at home with a babysitter on Shabbat mornings.
There is no reason why we should refuse to consider making women chayavot. We would just have to decide whether or not all Conservative women truly wanted to be chayavot en masse, or whether they were satisfied choosing obligation on an individual basis. And then, if the novellum were called for, doing it carefully and thoughtfully as a takkanah.