This already happens.

At the top of the Artificial Intelligence Area51 page you see this banner:

The AI site didn't have enough activity during the beta, and has been closed. You can download the data dump of all questions here.

You can see this on other long-closed proposals too.

Big Data is the exception here; I don't know why it doesn't have a data dump, perhaps it just had not generated enough data in it's mere 13 days of existence.

This is already done. Closed proposals on Area51 are given a download link to the datadump.

At the top of the Artificial Intelligence Area51 page you see this banner:

The AI site didn't have enough activity during the beta, and has been closed. You can download the data dump of all questions here.

You can see this on other long-closed proposals too.

Big Data is the exception here; I don't know why it doesn't have a data dump, perhaps it just had not generated enough data in it's mere 13 days of existence. Perhaps the missing banner is an oversight.

This already happens.

At the top of the Artificial Intelligence Area51 page you see this banner:

The AI site didn't have enough activity during the beta, and has been closed. You can download the data dump of all questions here.

You can see this on other long-closed proposals too.

Big Data is the exception here; I don't know why it doesn't have a data dump, perhaps it just had not generated enough data in it's mere 13 days of existence.

This already happens.

At the top of the Artificial Intelligence Area51 page you see this banner:

The AI site didn't have enough activity during the beta, and has been closed. You can download the data dump of all questions here.

You can see this on other long-closed proposals too.

Big Data is the exception here; I don't know why it doesn't have a data dump, perhaps it just had not generated enough data in it's mere 13 days of existence.