It seems that now (if you got the money and knowhow) can hybridize all the strains of yeast you want. It would be cool to mix a super aggressive strain like 1118 with something that gives better esters. Or perhaps make some that like really high temps without getting stressed, or one that likes it really cold. Have summer and winter strains.
I've thought about this enough to do a little reading, FWIW:
Yeast don't usually reproduce sexually but if you store a minute amount of yeast in distilled water, the starvation conditions makes the yeast go into "survival mode" and produce haploid spores. When food comes available the spores recombine and make new yeast in new combinations.
I've thought of sporulating two kinds of yeasts with traits that I want, say like a hardy fast fuel producer with one that ferments xylose and then feeding them to get the spores to recombine and then testing the results to see what I got.
It's so far down my "to-do" list though I don't know if I'll ever get to it.