I find your scenario entirely plausible!
I immediately suspected Nendou of having a mind shield when Saiki couldn't read his mind, and I wondered if everybody
in the series had powers... not along the battle-cycle manga stereotype Saiki thought of (in the chapter where he explained
how he altered the world with mind control), but I wondered if Saiki was, somehow, undergoing psychodrama-therapy for his
social shyness, and the other characters were his therapists!
Maybe not that far. But Saiki himself has lampshaded Nendou's absurdly-lucky 'guesses'... guessing the correct Saiki household
out of the 1407 ones that exist by that name and stumbling across it? Isn't that a little too much to dump on poor coincidence?
Either Saiki is subconsciously using his powers to draw friends to himself or there is something else at at work. Not necessarily
anything sinister, but it is NOT coincidence. (It could be pure comedy, in which case it will have to be handled correctly to keep
from getting very stale very quickly.)
Sometimes when I am reading a new manga and wondering what it will be like, if people have not already spoiled the genre, I try
to guess, Which factors of the first chapter/ first arc will remain and which ones will turn out to be mere mystery/ suspense-building
'cake frosting', so to speak...? Some of the most intriguing manga I have read have been those where it turns out that everything the
MC THOUGHT he knew was a lie, a hoax, a dream, etc. And then he has to get used to the changes so that life, and the story, can go on.
There could indeed be 'more serious' things going on just below the surface that we (and Saiki, at the moment) don't know about.
Character development would not be entirely out of place... it would just have to be handled very carefully.
Consider how little Teruhashi actually KNOWS about Saiki. He's never spoken to her! (ha-ha) But it seems to me that the ONLY reason she is
interested in him is that he is able to resist her power; i.e., that he has a defense against her constant transmission of feelings that drive men
wild for her. ...maybe it's NOT just her over-inflated opinion of herself. Maybe Saiki altered the world a little bit more than he realized, or meant
I love the little bits of consistency... Hairo is 'hot blooded' as a fire-user should be. But at the beach, Kaidou 'shorts out' in the water, as we would expect
someone with electrical powers to do! (Judgement Night of Thunder!) And then, curiously enough, when Hairo tries to swim to rescue a drowning victim,
he seems to lose steam.... Fortunately Nendou with his water-power has no trouble. He's like a scrubbing bubble in the bathroom-cleaner commercials...
"His power is released in water!"
There could also be another scenario. What if Kaidou is right about Dark Reunion being after the Jet-Black Wing...? If there was an other-dimensional
evil organization at work, Saiki wouldn't necessarily be aware of it right away. If JBW knew his physical body was about to be destroyed, then he might
try to project himself into another world where he could gain powerful allies in the fight against Dark Reunion! Now wonder he's so desperate to become
Saiki's friend! (If allies like Nendou, Hairo and Toritsuka are the best he can come up with, JBW is doomed.) Perhaps their powers are weak now only
because they are unpracticed.
Want to hear an even wilder scenario? (This falls partly under the heading of powers/weaknesses we haven't seen yet.) Suppose Saiki is temporarily
affected by some glowing radioactive meteors that neutralize his powers. The world will be destroyed and he along with it (so he's not being all noble
and altrusitic when he does this) so he must power up the others. Could Saiki stimulate psychic powers in the others or (again, only temporarily) LEND
his powers to the others? And the humor aspect could be preserved if Saiki had to resort to more and more ludicrous 'explanations' as to why they were
able to do those things, so that they wold BELIEVE it was only a hoax or a dream! I can imagine Yumehara OR Teruhashi, either of them, saying, "When I
saw Saiki-kun's body under the car, somehow I developed the tremendous strength to lift it from him before he could be injured! (Sigh) He inspires me so!"
Anyway, I look forward to hearing your ideas. These discussions make the manga twice as much fun!