The only problem with using "Yesterday's Enterprise" in that way is that audiences would be seeing Kirk and an alternate-Picard teaming up, which isn't really what audiences would have wanted. Also, the butterfly effect of the Enterprise-A being pulled out of time by a century would have had major effects by the 2370s, so the situation aboard the alternate Enterprise-D in the extant "Yesterday's Enterprise" would have been exceedingly unlikely. I suppose some of these things could simply have been handwaved away. I suppose.I remember reading somewhere that Berman felt that they should've kept Yesterday's Enterprise's plot for the first TNG movie and I think it would've been the perfect fit for a story that combined the TNG and TOS crews without short changing either of them.