My questions;
With this lineup for future 6 star content would you pull for CG Sakura?
Same question for future 7 star content, would you pull for her?
Are there any Trials or 10 mans that have constraints that CG Sakura does really well on where my other MAG units may struggle?
If you're talking all the way into the 7* era, then Emperor is more dps than CGSakura at 7*, assuming the boss is not immune to fire.
If asking about upcoming trials and 10 man bosses, then to briefly go over them for the next 6'ish months:
Moose trial -- faceroll with any dps
Iron Giant trial -- neutral to all elements, magic seriously favored here
Bomb trial -- immune to everything except fire and ice damage (including non-elemental)
Spear 10 man -- neutral all elements, magic damage required for phase2
Hammer 10 man -- weak to fire and thunder
Katana 10 man -- neutral to all
Dagger 10 man -- immune to holy, neutral to the rest
Hat 10 man -- immune to dark in phase1, immune to all but fire in phase2
Hope that partially answers your question.
The TLDR is that Sakura is better than Emperor for magic dps at 6*, but Emperor is better at 7* and "good enough" until 7* comes out. This is only taking into consideration their damage, and not extra utility. Sakura has some nice utility skills, but nothing unique that you can't easily get from other units.