As I said before..... perhaps it might be better to think of him as a entirely new character and not Daniel's replacement. If the producers have any sense they won't just fling him into a mission with SG1 without him having to be vetted somewhat first. If he is, then it will probably be a case of whatever knowledge he does hold will be vital to the success of the mission.
I don't know I am just guessing here. I have no strong feelings about it at all.
However, at the risk of someone decapitating me for mentioning that I was military, military teams are not generally made up out of close personal friends. They are selected for their individual abilities in the field. Yes they form a coherent team, but not to the extent that SG1 have been portrayed. SAS teams are put together from a pool of soldiers. Many of them will have served together on missions but they may not be a regular team. ALL soldiers are socialised to work as a team, it's the one thing which is drummed into you from the outset of recruit training. ALL soldiers are taught to watch each others backs whether they know each other or not.
I went on a brick (four man patrol) once through the streets of Belfast, I didn't know any of these guys from Adam, but because of theirs and my training, I trusted them to watch my back. Even in a regular platoon, yes you make friendships, very often close friendships, but sometimes people get killed and then the platoon member is replaced with another and life moves on. Whoever is the replacement you have to hope that they will watch your back the way you would watch theirs.
There is nothing emotional or personal about the military machine Hatshepsut. You may feel emotional about an individual in the team but at the end of the day, when your commanding officers say 'jump' you say 'how high?'. SG1 will be expected by their CO to do just that with whoever might replace Daniel. Jack would be consulted as the leader of the team, but ultimately it would be General Hammond's call and he would have to be practical. As the General Officer Commanding a base like SGC he cannot be seen to be dictated to by his emotions or by the emotions of his staff.
I do realise that the show is not real life, but if they want to have the sanction of the USAF then they would have to at least pay lip service to reality in the military.
Of course, in REAL real life, Jonas Quinn and Teal'c would not be allowed to wander around doing ANYTHING classified, nor would Cassandra have been allowed to be adopted by Dr Frasier. These people come from other planets for god's sake, do you really think that the paranoid US government would let them do what they want here? I really don't think so.
They would be held in some secure facility and interrogated extensively, as Adrian the Goa'uld was.
