im pretty sure its not extinct, 1st time i heard about dalat was in rosenthals ask ed columne in the year 2001, later on 2003 he (dee we dalat - his handle) did famous grow reports with hundreds of pictures and his writing was also nice to read, not those common grow reports, more like short story books ...
but back to the important details, he did indoor selections of the dalat, and by that, producing hundreds and thousands of seeds, which he gifted to all members who asked on the forum, its just a decade ago ... now the problem is, none of the official breeders would have intrest in that, as the fastest phenos went about 20 weeks, the middle phenos took 30, and those long flowering (2 season) took some 40 weeks, all those seeds are in private stash boxes all over the world, by private home growers, and i mean if some strains or cuts are held for longer than those short 10 years, it must be somewhere, dont loose the faith, the more you chase - the more it gets out of handsight
mark surf (his handle back then) had many and did also a good cross with c99, which got better results in the high department, as dalat to what i understand had 1st to be selected for indoor use by high and not for fast flowering times, and c99 was this missing link in the high, tho he just wanted to short things up, lucky bastard hehe
we r living in a fast consuming time and ppl just dont get it that good things take time, you r right about the fact that once the gen code is overwriten with neg indi info, it stays there for ever, thats life, thats the meaning of life .. expansion of the dna throughout the universe (talking about microbes from the moon or mars) .. we all have one in common, at this "material" stage, which is this amazing double helix .. sorry getting too philosophical .. but thats the result of good sativas, which open your mind, soul and heart .. after the big confrontation of your worst enemy - yourself, a reason why i like especially thos paranoia and fear inducing creeper sativas, any other emotion is just a abstract of fear, and by that you learn , you grow up and rise, i dont want to reflect further as it might lead into the wrong direction ...
and you know very well this story too

about the french man and his plantation, thats exactly dalat
i like your views on things, especially about haze ! anything today which has only 10% haze in it, is called haze, wtf ? like i order a choco cupcake which has a cherry ontop , its still a choco cupcake and not a bloody cherry lol
genetic interferance started even earlier (archeologically speaking), its the oldest and first global "product" we can date back by pollen analysis, even the famous permafrost özi had seeds when he died in the alps lol
its hard to find pure strains, as you correctly stated bc of money, africa is and would be my first place to start, as those selfproclaimed kings of weed and their amateurous hunter series only document their ignorance and greed, i mean arjan or gyppo "share" "fine" dutch gens and pollute natural strains all over the world, yeah they have the financial power to travell, but the backside is ignorance and strain wipe outs, and we all are left with hybrids from source countries, now some friends of the plant get some hands on some buds with some seeds, and they think they are genuine, they arent to blame, bc it was already polluted, and so my guess would be that afrika is the least polluted continent ...
i myself still wait for the black magic african weed, to get my hands on it, maybe one day .. no one knows
reminds me of qoute from trainspotting:
1,000 years from now there will be no guys and no girls, just wankers. Sounds great to me.
there will be no sativas and no indicas, just crap. sound horrifing to me.