I’m always too busy to sit down and look into this, but TurboTax 2019 kicked me into it.
I have a May 2015 MBPr 13” running Sierra and a 2016 iPhone SE running iOS 12
My fuzzy memory tells me that some programs stopped working in HS (maybe Ascent?) and was this OS when the file format structure changed? I think that’s what made me stop most of all.
Worst case I can move Ascent to my iMac or 2008 MP unibody.
My main apps are (starred are used daily to weekly)
*Excel 2011 (I do use Word but not as much) I tried Numbers for a couple of years, but have been using Excel since the beginning of time so it didn’t work out. Neither did many of my formulas.
*Fanuiro - billing program I was forced to after iBiz stopped working with Sierra
*iTeleport - remote access to some clients. I don’t like it much and have a couple of others I could probably use. Teamviewer is out
*Viscosity to tunnel into a VPN
*Microsoft Remote Desktop for client work
*Splashtop for client work
*Ascent (sometimes I think I should start a year with Rubitracks but old habits die hard and it still works)
Lesser used apps
Vuescan, but not as often as before and could probably move it to another machine.
Notability - used mostly on iPad but it syncs to all devices
Quickbooks Online desktop module - can use web version if need be
Things 2.x - syncing is stopping with Sierra but I still use it
Plus standard OS apps: Safari, Mail, Reminders etc
I also considered upgrading the iMac (which will get stuck at Mojave I think) but run an older version of iTunes on it along with my entire music library. My MPB forced me to move my library to an external drive so I was more than happy to set it up as a music server and Lightroom machine in my office. Sometimes I think I should bite the bullet and upgrade the MBP as far as it will go but I’m not sure I’m willing to lose Illustrator on a portable machine.