This is an important question! In my opinion data must be published (a matter of transparency and getting the maximum out of data) and archived forever using one of the services available e.g http://www.datadryad.org/ I posted this question on Research Gate as well. Lets see what comes out of this! https://www.researchgate.net/post/How_long_do_researchers_have_to_keep_records_original_data_of_experiments
thank you for this great question. I think today there is no excuse any more to “loose” or delete data.