Trying to avoid hijacking this thread too much:
I've never been to a convention, but I've met Rob Wilkins once or twice and saw Terry in a couple of signings. What kind of guests do you have, Molokov? *curious*
In past, we've had Terry, and Rob, and Stephen Briggs, and Ian & Reb from the Discworld Emporium... but the likelihood of getting international guests *in person* is very low nowadays. Instead, we've leaned on Australians who are big within the fan community - Ben McKenzie and Elizabeth Flux, who host the Pratchat Podcast (which I highly recommend); Tansy Rayner Roberts, a fantasy author from Tasmania who has also written a series of essays called "Pratchett's Women" (and her "Pratchett's Men" counterpart essays are being published in Speculative Insight magazine every few months), Folk-singer Martin Pearson (now retired), and the Writer/Director/Producers/Cast/Crew of the Troll Bridge fan film.
It's likely you've never heard of any of the local guests, but that doesn't mean they aren't good to hear talk about their work and how it relates to Pratchett; and also they're usually really good at speaking to Pratchett's work as well.
We do also try to get a lot of the international guests via video call - usually Rob Wilkins will call in for half an hour or so; Stephen Briggs, Colin Smythe, and Ian Stewart are usually happy to chat with us; Last year we got Marc Burrows on for a call (before he'd even announced about his shows coming to the Adelaide Fringe this year). We also enjoy talking to Rachel and Jason from Better Than a Poke in the Eye.
As for next year... well, no guests have been announced as yet, as only a few invitations have gone out so far. Any confirmed guests will be announced much later this year or early next year.