It sure seems that way to me. Each of them: Sola Scriptura, Sola Fide, Sola Christus, Sola Gratia, and Soli Deo Gloria all arose as privations, limitations,and denials or some real or imagined practice or teaching of the Roman Catholic Church (and, based on the Tubingen corresponence, we can say they are negations of Eastern Orthodox claims as well).
Since a negative cannot be proven, it seems to me that the Five Solas are dead on arrival. Since it is only with the Reformation that we find them explicitly articulated, any attempt to claim that the Early Church taught them is by definition unprovable. Sure, there are passages of Scripture and statements of the Fathers which seem to fit with Protestant theology better than RCC/Oriental/Eastern Orthodox theology (I lumb them together because the Five Solas more or less apply to them equally) but ultimately the most that can be done is to say that these are mere curiosities and difficulties for the RCC/Oriental/Eastern Orthodox because the burden of proof on the Five Solas is so large as to be insurmountable both by virtue of their nature as negative true claims and by virtue of their historical "lateness to the party."
It seems to me therefore that when you take a "bird's eye" view of Church History, the priniciples of the Reformation lose by default and the only theological disputes that remain are those within and between the various ancient churches.
A possible argument against this that I can see revolves around the accusation that I am assuming a priori that "ancient Christianity"= "modern RCC/Oriental/Eastern Orthodox Christianity." I suppos it could be argued that the correct procedure would be to draw a giant "question mark" over the beliefs of the earliest Christians and attempt to cull their beliefs from Scripture and the earliest Fathers without reference to later theology or history. The objection which I have to this view is that I quite simply don't believe that there is any such thing as a "plain meaning" to Scripture which can be said to exist outside of the Churches which have developed historically. In my opinion, God designed it in such a way that if the real answer doesn't exist somewhere in the traditions which we have then there is no real answer, Christianity is a lie. God never intended for the wheel to be reinvented. I admit, this attitude of mine kind of prejudices me against Protestantism from the start and also possibly opens me to charges of chronological provincialism in that all traditions which are now wre once new.
What do you all think? I'm not sure why I'm beginning this thread. It's probably entirely frivolous, but maybe it'll do some good. I guess I'm just trying to develop an idea I had today.