0.2 Spoilers and speculative spoilers for 0.3+ below, beware.
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0.2 spoilers ahead, you've been warned.
Going into 0.3 with MC forgetting to cliffhang (ouch), I suspect the MC won't stay in the original world for long as splitting a story between two worlds doesn't make much sense for this story when there's so much of this new world to explore.
First off they'll probably visit the burger shop with Cindy and visit Abby and maybe some of her AF friends as an obvious plug for a great game.
Later, MC wondering if it was all a dream, but realizes he can use magic and shows Cindy. Gaia detects this and investigates, says Ea messed up and didn't make sure MC's original body was actually dead. Won't let magic exist in original world and decides to send MC back and Cindy has to have her memory erased or go with MC.
If they're lucky they get to take their stuff from the apartment, if really lucky, a download of wikipedia. It will be interesting to see if MC can leverage technology or will go native and stick to magic alone. MC and Cindy probably won't be back to original world again, except maybe in flashbacks or the epilogue.
Some long term goals for MC on the light path: learning how to remove runes, maybe for everyone.
Anyway this is all just speculation. The story is off to an excellent start. Combat could use some variety.