Prior to reading your pdf, I’d like to share some generalized observations (obviously not intended in any way as criticisms as I haven’t read it yet!), then read your idea and afterwards comment on the pdf.
One of the main differences and problems between 2nd ed psionics and 3rd ed versions of the same, is the timescale in which combat was supposed to take place. If I recall correctly, 2nd ed psionic combat took place practically instantaneously, in the span of a mere glance, and had little to no observable side effects. Thus they were also invisible, untraceable, and effectively unavoidable.
These were among the reasons 2nd ed psionics was decried as overpowered and unbalanced, thus being ignored by so many DMs, an attitude which has been carried over into 3rd ed by many without much reservation, sadly.
In 3rd edition, psionics was firmly tied down to the same timescale as spells. Everything took an immediate action, swift action, move action, standard action, full round action, or 1 round (or more) action to manifest. Attacks of Opportunity would provoke in most cases, same as spellcasting. They were also given “displays” which meant that they were no longer “invisible” or “untraceable”. Gone were the days of having a completely separate combat system for psionics. Combat modes were now powers and fit in with the same combat system as melee, ranged, and spellcasting. These four things were very important aspects to making psionics fit with the rest of the game.
The mindscape based combat is a narrative mode which makes for great storytelling, but is very difficult to pin down to mechanics which still allow non-psionic types to participate meaningfully during the rounds of psionic combat in a game session - which is part of the reasoning behind the 3rd ed changes to psionic rules. Previously in non-Dark Sun 2nd ed, everybody had to stop and wait for the psionic types to get it over with before they could take their turns.
Now, in a Dark Sun campaign, that was be less of a big deal in 2nd ed, as everyone is psionic, explicitly as per the campaign setting. However, for various reasons, Athas.org writers made the decision to nix that part from the 3rd ed campaign setting. Everyone is NOT psionic, not everyone has a psionic power, and in fact a very large chunk of Athas.org’s products are filled with spells and spellcasting and magic-based prestige/classes instead of powers and psionics and psionic-based prestige/classes - something which I’m known for complaining about.
As such, does your psionic combat system require a return to the 2nd ed assumption that everyone is psionic, or does it gracefully handle non-psionicists as well? Furthermore, it is important to note that narrative combat is always an option, no matter what ruleset one is using, however most groups don’t bother to translate the miniatures-based mechanical combat of 3rd ed into a narrative mode. Also, the stealth-combat that is occasionally described in the novels is considered too difficult to pull off by most groups, despite the fact that it is entirely possible with existing 3rd ed psionics rules.
In any case, there are two main aspects for consideration in any revised 3rd ed narrative psionic combat system: one, does it recreate the look-and-feel of Dark Sun psionic narrative combat? And two, does it fit in with the existing 3rd ed psionic rules, and by extension, does it work in a setting which no longer requires everyone to be psionic as per Athas.org’s revised setting rules?
Having made all of these pre-read comments, I’ll now go and read over the pdf. ^^