Hulu listing an end-of-June expiration date for virtually all of their shows on there and the couple that may not list an expiration date yet are likely just not updated with it but will expire anyway.
With a couple of dozen series and hundreds of episodes, it looks like the continuing changes in the streaming sphere will see these titles depart shortly.
Sentai Filmworks had been loading up a number of anime series on Hulu over the last couple of years in order to expand their reach and draw on more audiences that would also potentially want to buy the home video releases for them.