Australia is not in great form at this moment, but the same can be said about Bangladesh as well. The advantage for Australia is that they are a well balanced side, while Bangladesh is overdependent on a few players. But I am not discounting the possibility of any upset. First of all, the format is T20, and on top of that Bangladesh has the home advantage. It is a five-match series and therefore it may be difficult for them to attain a series win. But I am sure that they can upset the Australians in at least 1-2 matches.
Australia won the toss and elected to bowl. I have just seen, Bangladesh lost 2 wickets and they scored 53 runs. Many players of the Bangladesh team seem new to me, did you notice that? Soumya Sarkar and Mohammad Naim went down in the opening, lol...
Although Soumya is a somewhat experienced player but I think Naim is a new player. Naim was dismissed for 30 runs off 29 balls. Now Mahmudullah and Sakib are at the crease.
I think the Australian team is well-balanced now than Bangladesh as you mentioned above, Don't see enough good players in the Bangladesh team.