I think we’d get used to it very quickly. I think one of the symbolic strengths of the EF is the priest facing ad orientem at the key sacrificial moments of the Mass. I cannot see why this couldn’t be included into the OF Mass. So long as the priest explained to the congregation why he was going to do this, and was open about it in advance, explaining the rationale, I think most OF congregations wouldn’t have a big problem with it.
Even a bit of Latin used in the OF wouldn’t be an issue for most congregations. Just so long as the priest doesn’t start reading the scripture in Latin, which I do think is a pointless thing to do, even in the EF Mass. I think it was pointless reading the Word to the people when they don’t understand what you’re teaching them? It makes about as much sense (in my opinion) as giving a sermon in Latin.
Personally I’d like the OF Mass with a bit more Latin (but with the Collect, Confession, Scriptures, Gospel, Creed, Prayers of the Faithful, Our Father, etc) absolutely always in the vernacular, and I would have some use of ad orientem position. I’d also like some incense from time to time.
There is very rich symbolism present in both the OF and the EF Masses, I don’t see why we have to choose either one set of symbolism or the other. Why not include the best of both worlds? Perhaps Pope Benedict’s Summorum Pontificum on the EF Mass was a sign to us that both types of symbolism are necessary to help us have a fuller understanding of the Sacrament?