The problem with maintenance cost isn't in keeping the current system and code running. Obviously it will handle the small population just fine. The problem is investing any cash in modifying the code to fix bugs or add new anything.
Any change that is made, new content, bug fixes all have to be QA tested. That's a crew of people to ensure that balance isn't broken by it. Yea you can say that the players can test it. well yes, but someone has to analyze the data collected and approve it through the Higbys and Smeds and others that have final say. It's not like there is just one guy needed to modify all of this it really is a team effort.
Plus add on that the original dev crew isn't there, someone has to learn all the quirks of the code that exists and then "hopefully" make some positive chnages to it.
The PS:Next idea was to upgrade the graphics. The ease of this is that it would theoretically take minimal if any changes to the core codebase. The graphics are another layer of technology that can be manipulated secondary to the core. The core calls the graphics libraries to say "draw this", "color this". I almost bet that TRay and team got started down this line and said, ok we can only go so far and someone's going to have to change the calls being made. When faced with the decision to invest significant amounts of real resources into PS or invest significant resources into something new (PS2), the choice was easy as getting a revenue stream out of PS2 was going to be much easier than resurrecting PS1.
I honestly like PS2 graphics and UI and the experience of running around shooting people, but it's nothing like PS1. TTK is to short. certs are stupid, class even sucks, hacking somewhat useless, etc, etc. I could go on and on about how it isn't like PS1 like the dev team said it would be. It would be so nice to see a server that implements some of the things they said would be in PS2 that aren't. The problem with trying this now is the same as PS1. Having 2 separate codebases, 2 separate QA teams, double the expense.
The ship has sailed and I doubt that PS2 lives for long enough to implement it's roadmap as there are too many shooters coming up.
The bottom line is that I don't believe anymore that there is a playerbase for a game like PS1 in todays world. Yea I agree it'd be superior to any of these jump in and wack a few guys then log off shooters, but so few seem to have the attention span to work within a squad, to design their toon to fit their playstyle, to patiently wait for some dirty vanu to walk past your boomer, etc. Everything is thrown at us all at once. When I started PS2 I could drive, fly, shoot, heal, repair, and max. I think the only thing I couldn't do was AA max. Really?!?! Think about it. Everyone is only certing up to be better at what you do, not like in PS1 where you certed into things "to do".
I'd say just let PS1 run for free on what, a virtual server someplace. Noone at SOE wants to touch the code.
They weren't clueless about their business plan, it was to let it sit and leach money off of the handful still subbing. When the idea came to make more with a graphics refresh, it didn't pan out and Forgelight came available. Someone needed to test the engine to work out bugs before EQ:Next was released, so PS2 was realized. We're testing for SOE's cash cow and they're making money in the process. many game companies do this for new engines. It's just that PS2 hits perfect between a lull in shooters, just wait a few months and see the pop drop to nothing when the FPS big names have their next titles. But by then it won't really matter, PS2 has made significant revenue and EQ:Next will be out for the RPG fans. PS2 will have paid for itself and will be complete in testing netcode, graphics, etc to ensure the EQ:Next release goes much more cleanly. That's what I'd do anyway.
P.S. Before someone says well they made EQ F2P, look at subscription rates and revenue. Now compare that to PS. The revenue stream from EQ was and still is many many times greater. Although someone did make the valid point of no license fees for EQ and PS.