Personally, I don't really care whether it happens, I view Tremily as another one of those ships that fans force on two unlikely characters. If Kazu wanted Tremily, then he would have incorporated something, anything into the novels, or maybe even shipped them in an earlier book. Kazu most likely showed Moze to Emily to show the readers that Tremily is very unlikely. And seeing Emily's reaction to seeing her son and not a husband, I would say that she is nowhere close enough to the age where she focusing on marriage, she's probably going to meet her fiance in book nine. Any marriage or relationship between Trellis and Emily would be weird and down-right wrong. It would be like Emily marrying a dog. I'm not saying Trellis is a dog, but he is an alternate species, and suggesting there can sexual relationships between two different species is quite strange. Ultimately, there is a 90% chance Tremily will never happen, and even if it does, it's not going to be romantic unless one of them bumps their heads really hard.