Considering that mobage stories tend to be released in a piecemeal manner with new story chapters sometimes taking months on end to release, are you concerned with how long this might take?
Considering how long Umbra itself might take on the great scheme of things, not really.
But I am a bit concerned still because we have no idea what they plan on showing with GoS. There are a few things that could make us go "Well shit." up to including:
-Showing what young Julius Belmont did look or think like.
-Speaking of certain characters' involvement or NO involvement.
-Speaking of what caused Dracula's defeat in more detail.
-Speaking of something AFTER a piece of Umbra is out that is contradicted and can no longer be fixed.
Some things can be adjusted for, some can't. In the case of the some that "can't", we will strap ourselves to one of the project's mission statements: We only aim to present a plausible version of this story with our silly headcanon. We have our feet on the ground and we know that we're ultimately nothing more than a fangame.
This is also how we will deal with the possibility of Konami releasing an OFFICIAL 1999 media. In case they do, we will just move forward with our fanfiction as "solidified headcanon" because that's what it was always meant to be. In fact, their releasing an official 1999 media scares me much less than them releasing other piece of media
around the 1999 storyline talking about it (which is also not a lot of "scare", just a bit, like I said above), because a supporting media forces me to collect info and follow the breadcrumbs, an actual 1999 media does not -- it flat out tells me "you're wrong, here's the official thing" and I go "oh ok but fanfiction is not wrong tho".
On where we CAN make adjustments, we will, I promise, even on the stuff that takes months to get revealed. Konami being god, Umbra follows it like a devout unofficial and not-endorsed cultist doing what it says. I had to sacrifice a relatively minor thing that was in place already due to GoS speaking too much
but the plan B might be just better than what was in place before, who knows? I have one million plan Bs still