I think...saying you are not interested in JRPGs and not considering SRPG's just a different category of JRPG is very confusing.
That's what they have been making the whole time, the games in that mindset. So when it comes to a location and lore shift, what happens next automatically would be considered just as accepted to the authors.
If you are literally not interested in anything besides VC1 type gameplay and world view specifically, they were not going to hold the interest of those fans for long anyway.
I like Disgaea, Fire Emblem, Final Fantasy Tactics, and I'll even throw Super Robot Wars on here for good measure, but they're nothing like traditional JRPGs in terms of structure
In traditional JRPGs there's towns, dungeons, shops, side quests, inventory management, NPCs. I could keep listing elements, but I'm sure you're probably more familiar with JRPGs than I am.
In SRPGs, most of that fat is cut. It's just missions with varied, tactical objectives and in-between story stuff and team management. Disgaea blurs the lines a bit and it's probably my least favourite of the SRPGs I've played because of it, but it's still a huge departure from the structure of traditional JRPGs.
From my perspective, the lore and idea behind Valkyria Chronicles - fantasy WW2 with Norse mythological elements thrown in - is interesting, but not as interesting as the gameplay elements.
I feel that the shift from SRPG to JRPG would shine more of a light on the characters and the world, which - in my opinion - has never been the strongest point of the series. The writing has bordered on being 'too anime' since the beginning and Valkyria Chronicles 2 shows what happens when that line is crossed. You get a game that people praise for its gameplay with the caveat of 'if you can suffer through the characters'.
When I said that I'm not interested in another JRPG, A more specific way of putting it would be 'I'm not interested in a by-the-books JRPG with characters that have the depth shown in past entries in the series, particularly if they're not backed up by enjoyable gameplay systems'.
By all means, if the emphasis is put in the right places and the characters are built up more than they have been in the Valkyria Chronicles series without falling into the gutter of tropes that plague anime characters while simultaneously being given a good gameplay system as a backing, the game could be great and give new life to the series.
I just think it would be a safer move to redo the old stuff and make sure everyone has access to it, generate some money and goodwill within SEGA and the western community and
then go on to make your experimental JRPG spin-off thing. If it doesn't work out. If it fails, then SEGA might give you a chance to make VC4 instead of kicking you to the curb at that point.