We're looking at a retrogradational scenario - that an initial rise in sea level causes a transgression but that in this new geometry the sediments are more effectively trapped on the shelf and it then progrades rapidly. The country of Bangladesh is an example of this on a 10,000-year timescale with 100m+ of sea level rise at the end of the last ice age (flooding the low-lying former delta), and now the delta is rebuilding. Give it time, and it'll get back to where it was before. But it'll need a lot of time.

I'm working at the moment on a sedimentary system in the Gippsland Basin, Australia where tertiray subsidence led to transgression of the shoreline by over 100km over a time span of 40 million years. That's an average of 1m every 400 years, but superimposed on that trend is a vast and complex history of floodings and rebuilds of the delta system. Coals trapped behind the shoreline belt attest to the former geometry and we're piecing together a very detailed history of the basin right now for use by multiple end-users including potential CO2 sequestration (yeah, I get an each-way bet on petroleum!)

But this is subsidence at a geological pace. What AGW offers is a bit more of what happened at the end of the last glaciation - then, sea level rose by ~100m in a timespan of only 5,000 years or so - about 2cm per year. IF there is a sudden burst of global warming, then sea levels will rise, there will be a transgression, and then we start building the deltas out again.

People in low-lying coastal areas lose out - During glacial times, Sundaland was probably a garden of Eden, with low-lying fertile land connecting Indonesia, Malaysia, and Thailand in a giant swampy jungle. Now it's all gone - or rather transformed into an oceanic zoo of coral reefs, shallow seas, and dynamic marine ecosystems.

On a geological timescale, everything changes, but life goes on. Millions and billions of individual animals and plants live and die, but species generally continue (and slowly or more rapidly evolve)