Speculate however you want, resources not spent on KH goes elsewhere whether they outsource the game or not. Square Enix is solely responsible for funding the games development.
I mean...yeah? Resources are always going to be allocated to projects depending on scale and importance. Also, Disney partially funds Kingdom Hearts.
FF7 is going to obviously get more of Square Enix's money than KH because it is a project they have full control over and finance on their own (with some of Sony's money). KH is not under SE's full control, so it gets less funding from them. And it gets exactly whatever Disney is willing to give because Disney is Disney.
And the pandemic has only been a hindrance in the last few months, this has been an ongoing issue with Square Enix for years. Kingdom Hearts has slowly fallen to the wayside and the few developments there has been were used to exploit the fan base.
KH has always been the odd ball project of the company. It's been clear since 2002 when the game first released. It's never been allocated the kind of resources you'd think it would deserve, and it has always been under FF. It always will be.
KH hasn't fallen to the wayside. It's exactly where it has been for almost 20 years: considered important but less important than their other flagship property, and KH3 has really only just brought it out into the limelight and solidified it as a true tentpole for the company.
Regardless, I think your argument goes against fact. We have multiple projects in development for Kingdom Hearts, one of which they intend to announce "soon". Dark Road is a smaller project, and likely more of a passion project for Nomura and the UX team given the fact that this game wasn't going to exist at all until the UX team took it up.
Just because this one game is probably delayed doesn't mean Kingdom Hearts is some neglected and under-appreciated project at SE and is having all of its resources siphoned by the FF7R team. There is a whole department whose main task is making Kingdom Hearts games with multiple teams within that department working on individual projects. They have a lot of money to work with thanks to the success of KH3, and Disney seems to actually recognize it as something worth putting more of their own resources into now because of KH3.
If Kingdom Hearts was in a bad place, we'd know it. We know it isn't because Nomura would not have been quick to announce multiple projects being in development. There would have been a lot of "well, we can't talk about anything atm" or "we are in talks" or "there is nothing to announce". Instead, flat out we got "There is one game coming before KH4, and we also have four teams working on KH projects"
Like that doesn't sound like throwing KH to the wayside to me. Sounds like we've got more projects coming our way than we are anticipating. We've got the Osaka team that just came off of Remind, UX/DR team, a team working on the project coming "soon", and a mystery team making who knows what.
Imo, if they were far enough along that they could confidently say it would be released in "spring 2020" then the coronavirus wouldn't hinder it much anyway, but they haven't even bothered putting out a statement.
They have production schedules. This virus has interrupted those schedules. I don't think it is hard to figure out what is happening here with this project.