You are complaining about alack of cash inflow from Symbian!? Well I can tell you why...
You sticked to your own widget set and your own very limited UI while most models have moved to full touch only input, your software was only powerful in combination with HW keyboards. All the shortcuts needed proper touch integration.
With C++, Qt, Qt Quick QML Components you could've used your backend and easily provided the BEST experience on the whole platform and even price it apropriately. You lacked only a PR department effort to push your softare, no social channels, no effort to push it to Top OVI sales by afew tricks.
That's the reason on why nobody bought it.
Take a look at your own provided data on that wiki link, Symbians deployed user base ist still the second biggest, yet you don't support them anymore. It's because of opportunistic developers like you that the platform itself became unviable for you.
Sad to see it discontinued sincer there are so many issues that still needed to be adressed.
Good Luck out there! You should've at least open sourced your app if you don't provide any more support and don't gain cash from it. I wished for the same for JBakTaskMan so that at least in community efforts a UX/UI overhaul would have been possible.
Your reputation is beeing hurt if you let X-Plore exist in its current form.
Hope that at least someday we get some equivalent!
Cheers from Germany