Really, its a case of what Apple are going to do now if they want my cash in the future. I have no desperate need to upgrade, and if my equipment fails the current rMBP would still feel like an upgrade. What Apple needs to do is produce something that makes me want to upgrade without waiting for an equipment failure.
My 2011 17" MBP does everything I need, really: I'm stuck on 10.9 because of my ExpressCard-to-USB3 adapter & because I use ScreenRecycler to run 2 external displays - but currently that's not really a problem, and its soluble via Thunderbolt devices. If it goes bang and I need a new machine overnight, then I wouldn't feel too bad about plumping for an existing rMBP.
Or, I've long been tempted by the 5k iMac - which was bumped to Skylake at the end of last year, so is relatively up to date. If I needed more power I'd have built myself a ludicrously overpowered Linux or Windows PC ages ago. However, I have grown to like having everything I need on a laptop that I can shuttle between home and work.
What is really holding me back, though, is the prospect of USB-C/Thunderbolt 3 and single-cable 5k support - I'd really like to know what is going to happen there. However, I'm not sure that the rest of the industry has sorted that out, either: it still seems to be undecided between USB-C (USB 3.1 + DisplayPort 1.2/1.3) and Thunderbolt 3 (TB3 + USB 3.1 + DisplayPort 1.2 only) and whether USB-C really will be the universal connector in the next few years, or if it will be just for phones.
Looking at PC hardware, nobody really seems to have embraced USB-C/TB3 apart from Google (and I don't want a Chromebook) and possibly the Dell XPS-15 - even there, they've gone for a single USB-C/TB3 socket as their charging port, effectively making USB-C purely a docking port. On the desktop, some motherboards have a single USB3/TB3 port alongside all the usual "port salad" (do I really need PS/2 or DVI-D? How about two video connectors of the same type so I can connect dual displays without silly permutations of cables?)
In the past, it would be Apple who nailed their colours to the tree and went all in for USB-C.
I'm wondering if Apple is holding off any radical changes until the situation stabilises.
If I was tempted, then its the Dell XPS 15 + their TB3 dock, or the Skull Canyon NUC - both at Apple-like price premiums.
I could live with Windows or Linux if I had too - probably Windows "front end" with Linux VMs.
The WWDC keynote would have been fine - major improvements to WatchOS (which is in its early days) and minor refinements to iOS and macOS (which is mature and doesn't need a massive annual overhaul) - if it wasn't for the fact that the Mac Pro, the Mac Mini and the rMBP are all crying out for updates & we need to know Apple's direction on USB-C/TB3.
If they'd announced that they were holding back on TB3 for another 6 months then I might have succumbed and ordered an iMac or a rMBP (which still attracts me more than a Dell).