Nocturnal Sect really isn't bad at all anymore. It's a fairly decent alternative to having a Scholar in most respects.
Aspected Helios always was, and still is, a perfectly acceptable alternative to Succor.
Aspected Benefic used to be an absolutely terrible alternative to Adloquium; now it is arguably the stronger of the two.
Having access to Benefic II and Helios is the equivalent of having Emergency Tactics with zero cooldown.
GCD heals as a whole are now significantly more MP-efficient than their Scholar equivalents, without sacrificing any power - in fact a few are more powerful.
The 5% Nocturnal Sect potency bonus is, to be sure, significantly weaker than having Embrace, but that's balanced out by having an overall stronger suite of baseline GCD healing.
Scholar's Aetherflow-consumer healing toolkit is fairly evenly matched with the new AST cooldown suite of Collective Unconscious, Synastry, and Essential Dignity. Lustrate/Soil/Indomitability rules the roost in terms of moment-to-moment versatility, as Scholar has always done, but AST having discrete cooldowns means that their skills typically don't have the opportunity costs that Scholar has to deal with, and Synastry/CU/ED tend to beat Scholar's tools in sheer power.
And while it's generally not an apples-to-apples comparison, the AST cards are about on par with the non-Embrace fairly skills, when it comes to the magnitude and variety of effects.
I don't expect to see many Nocturnal Sect Astrologians taking the place of Scholars in serious progression, but that's no longer due to any real deficiency in their ability to heal and shield; it comes down entirely to Scholars just being so well-suited to DPS that it's very difficult to imagine any dedicated healing class/job being able to catch up in a meaningful way. There are adjustments you could make to Astrologian to try to close that gap, but the problem doesn't really have anything to do with Sect choice, and neither would the solution.