Gravel / Gravé / Gnarmac / Groad / ATB

Has anyone got rid of their bikes and gone down the one bike does it all route? I live in London with 3 bikes currently:

• Boardman CX set up with a rack, mudguards, and 32 mm tyres. I do 80 - 90% of my cycling on this bike and enjoy it. I do a 9 mile commute and short trips round town.
  
• Cotic Escapade fixed. I built this up with some nice bits earlier this year - Thompson, handmade Hope wheels, decent front disc, etc. This gets used a couple of times a month round town.
  
• Genesis Tarn fully rigid 27.5 x 2.8". Gets used a handful of times a year in the Surrey Hills, Scotland, Lakes etc including a couple of bikepacking weekends if I'm lucky.
  
  

I'm so busy with work (junior doctor), kids, etc that I don't get much time to do a lot of cycling never mind fettling bikes and also we've limited space living in a flat. I've also recently been diagnosed with a rare disease that has basically destroyed 1/3rd of my lungs and will only go in one direction.

With that in mind it's appealing to go down the gravel route and just have one bike that does it all - more space and only one bike to maintain. Something like the Arkose X or Genesis Fugio 20 (2019 on sale at the moment for £1100 and 0% finance at Evans) that is basically a drop handled MTB that will take 2" MTB tyres but I can stick some mudguards, rack, and proper road tyres on for commuting. Although I only ride MTB a few times a year I love these opportunities and don't want to be hobbled too much by a bike that is too much of a compromise.

If I sell my bikes will I just end up regretting it? Thoughts appreciated from those that have done it/considered it.

Cheers!