You got one source. There are other sources that say it will happen sooner. Many other sources and these sources are not obscure.

Given multiple sources saying different things, It's hard to predict. Though what we are seeing are feedback loops that are causing exponential effects. I would say although we don't know... before 2100 is a realistic and viable possibility.

Gambling solely on 2000 years because it's a more convenient prediction would be unwise.

Either way, even if we don't know, now if sea levels do rise at a pace that will occur before 2100 we would eventually see it and adjust our reaction speed accordingly.