Hey guys, no one said you can't get an in-game Celebi still. What we know is that Celebi has to have its Fateful Encounter flag marked to activate this event; it's pretty probable they'll distribute one in Japan next year, but who's to say we won't get an Ilex Forest Celebi too, also with the flag? Platinum Shaymin has the same flag, just like Movie Shaymin.
The difference is that in Platinum, hacking allowed us to access both the Darkrai and Shaymin events. Hacking has led to no such discovery of an Ilex Forest Celebi, meaning that it is essentially non-existant.
On a side note, Johto Safari Zone has Murkrow and Larvitar. I've found both of them already. Some people have declared Misdreavus is also in, but I haven't found her yet. And no sign of Slugma and Houndour still.
Thoughts in bold.