First I am not a con expert cause I kind of find them a bit just too gimmick to extract money for the most fervent fans but I know that other have canceled in the past and even colin did! Second there a warning that actors and actress can cancel from the con itself and speifically jen herself state that her appeareance will be depending of her schedule!
Also, Jen is in the same boat as Emilie so if she dont do con for that reason alone emile de ravin should have the same problem as well! And, without really make any search I saw that there rumour about her and Bex not being invited back either. If thruth it sound one of the real reason is too invite the new cast.
Now, for jen not being a draw I saw that she and colin actually was sold out in the last when even lana was not at the time. So, she, colin and cs definitely is one of their biggest draw adding that the rumbelle con this summer didn't had the same succes at selling ticket and attendance that from one of the biggest rumbelle shipper who was in attendance at the con.
So, because I don't think jen will be as much open to others type of con cause of some past problem with them I hope that they will reconsider and for the fan invite her at least at some same for Emilie and Bex. I really dont believe any new ship or cast can and will beat the original cast and ship as draw.
Lastly, I find rather funny with the multiple time this show, showrunner have mislead and lies a lots of cs fans first and reaction his to trying to put all the blame on jen and all the situations! Never grey, or multiple factors always the simple atavic reaction it somehow must be jen liying or fault. I wonder what about her that brought that reflect so easily? Being beautifull, ambition still is a problem to some? Genuinely wondering ?