That's then a nice setup for either Carol's 3rd movie or a separate film entirely. I'd have lost the plot if that was what I watched!!
The mid credits scene could have been Carol waking up somewhere on this (yet to be revealed) alternate Earth and find some woman with a skunk stripe in her hair standing over her, asking where she came from and what she's doing. I'd have loved to see Carol do the self-sacrifice bit at the end of The Marvels, rather than Monica.