Just one users 2 cents:
If you really feel the need to upgrade, I would upgrade everything, and there are a few reasons for this approach.
#1-it leaves the old rig fully functional(handy for multiple reasons)
#2-it allows you time to get used to all the new stuff before moving the old setup to a closet(or craigslist
)
#3-you avoid the pitfalls of trying to get some old stuff(like the 003) to work with some new stuff(like a new computer.
As said, its a crapshoot as to whether the 003 is going to work(its way past its end of support). Then, there are plenty of new interface options that will sound better, and use Thunderbolt 3 for very low latency(assuming a low buffer setting). I would suggest either a 27" iMac quad core or MacMini(fastest clock speed you can get), 16GB of RAM and a TB3 interface. Of course, a recent(or new) OS is going to require the latest Pro Tools*. And depending on how much you need the surface functions of the 003, there are a few options. For me, transport controls are most important, so the original Presonus Faderport covers that nicely, and I like the buttons for switching between EDIT and MIX windows(and I hate that the left those off of the new Faderport
). Stepping up, a DOCK(with tablet) is great, as is the S1.
*just an FYI, since you are used to LE8, be aware that your old sessions SHOULD open fine on a new setup, but new sessions will NOT open on the old setup unless you save a copy in the older PT7>9 for format. And, if you are working with SD II audio, its time to convert everything to wave format
Re EZdrummer, you probably will need to upgrade to EZdrummer 2(which will run in AAX 64). If you own any EZX expansion packs, those should still work(if budget allows, Superior Drummer 3 is even better). All your old Instrument tracks will probably playback fine with the newer TT plugin
Last word of advice, when shopping for a new(er) Mac, avoid the Fusion drive. Get the biggest SSD you can afford.