No question the rest of the coaching tree would be considered, but of them all JenR is the only one with the USA HC experience as well as the college HC experience. Tonya and Jamelle are in their early years as HC, but given that Geno is around for a number of more years they will be better seasoned before the decision will be made, and they are both in what would be considered higher level jobs than Hartford.
And nothing says the job would go to someone 'in the family'. It should be a plum job whenever it opens up and the AD will have a lot of candidates to choose from. I suspect Geno will have some input, but you never know.
On shift from assistant to HC, along with all the added responsibilities, there is a major shift in the way you interact with the players. I think Jamelle mentioned that in an interview. Assistants can be player friends, advocates, and buffers between them and the HC. As a HC you are the one being buffered. And you no longer have fellow assistants, you have employees. It is a big shift in the way you interact with everyone and can be very tough especially if you are promoted from within.