Yes, a legit hackintosh in a nice apple made case. That's what professional users NEED.
Its what pros need, its what "power users", hobbyists, tinkerers and gamers need.
Its what developers probably don't need but would quite like.
It's what customers who are probably going to supplement it with a MacBook and an iPhone need.
Its what the sort of people who recommend Macs to their friends, family and colleagues, or act as unofficial "Mac Support" staff in their PC-centric workplace want.
Its probably not what Apple are going to do, because if you actually read the press conference transcript, all they appear to mean by "modular" is "no built-in screen or keyboard".
10-15 years ago an affordable "xMac" tower might have bankrupted Apple by cannibalising mass-market sales of iMacs and MacBook Pros. Now is not then - most consumers now <i>want</i> an ultra book or an all-in-one. The new reality is that there are probably not enough "Mac Pro" customers to justify the R&D and tooling up costs of something like the nMP (or even the original Cheesegrater with it's bespoke internal layout and cooling) whereas an "official hackintosh" would be pretty straight forward.
I'm not so totally naive as to think Apple could just follow a "how-to Hackintosh" guide and sell the result - but the existence of Hackintoshes proves that an ATX/ITX Mac with off-the-peg components* would be a relatively simple process of writing and/or testing boot loaders and drivers c.f. building a bespoke motherboard, bespoke GPU cards and fancy miniature cooling system.
(* if they don't already have one sitting alongside the ARM-based Mac, the XCode-for-Linux machine and the MacOS Subsystem for Windows box in Room 101 in Cupertino).