shirou wont have archer's arm but he will develop in the same pace ubw shirou did i think?but he would mostly won't play an important role at best he can be illya's bodygaurd and focus on protecting her.
the only servant remaining are archer,saber,rider,true assasin and berserker.
berserker is weakened and true assasin sucks so he wont have problem with both of them.
saber and rider is where things get interesting.
i don't think archer would have any interest in saving sakura since she tried to kill rin and illya so rider would be his enemy.
there is a change rider will form an allience with shirou and illya would probably help shirou but i am nt sure and if this shirou develops at the same rate of ubw shirou then he would have become adept at projection/tracing by this point on the same level of ubw shirou but not in the same level of garm HF shirou.
we do know saber alter went easy on shirou but would she do that for archer?does she even knows archer is shirou in HF?
so basically this will most probably be the scenario
sakura and saber vs shirou,rider and illya vs rin and archer.
where shirou,rider and illya would probably try to save sakura using rule breaker.
rin and archer would probably try to kill her but again i am not too sure.
the outcome will be decided depending on the sequence of battle.
i dont think shirou and rider can beat anyone so they will let rin and archer fight sakura and saber.
rin would fight sakura and archer would fight saber.
if saber is serious and decide to excallibur spam archer is fucked. however if archer use ubw or somehow weaken saber shirou and rider could win against saber before she recovers.
rin wont have azoth dagger so she probably loses.
shirou may be able to rescue sakura using rule breaker.
now here where the problem lies shirou does not have archer's arm so there is no way in hell he could trace excallibur.hoever sience he does no have archer's arm his condition will be far better.
i really dont know what happens after this.
this in just my interpretation what do you think?