With a POD in the early 1800's we have to consider:
1) the size and the autonomy of the Romanian Principalities in relation to today's Romania;
2) The sparse distribution of Romanians outside the Principalities (IIRC Romanians were a small plurality between Magyars and Germans in Transylvania and the Aromanians were just a small group of wandering shepherds in Turkish and Greek lands);
3) The lack of an influent national aristocracy as most of them were Greek Phanariotes selected by the Porte;
4) The poor economic background of the country: 10% of the population of the Principalities was made of Roma Slaves (IIRC Romania was the last European country to have slaves) and the rest of the people were just serfs;
5) A considerable part of modern Romania was populated by different ethnicities since the Middle Ages (Dobrudja, Most of Transylvania...).
So, taking all this into account, IMHO Romania was already GREATLY wanked in OTL if we compare the situation in 1800 with that one after the WWI.
By the way, I'm sorry if I offended Romanian people. Not my intention.
Regarding this there's another point to be made: if Austria manages to secure both Wallachia and Moldavia during the 18th century and they manage to hold on to them late into the 19th, then instead of Austria-Hungary we might have an Austria-Romania or Austria-Wallachia, but that's only if things go relatively the same as OTL, which isn't that likely.
This wouldn't mean a large influx of other nations into the Principalities? First the Greek and South Slavics fleeing the "Turkish yoke" and later the Germans and Hungarians from the HRE and Austrian Dominions, making the Principalities a melting pot like the Banat or Transylvania? This wouldn't be bad to a national identity after all?