(this is a feature request on behalf of he:User:Aasrsa17 suggested in he.wikipedia)
It would be nice to have ability to save reading list in cloud (e.g not locally on the device), so:

1. It would be possible add an article to reading list using Wikipedia website, and later on access it using Wikipedia App.
2. When someone replace his/her smart-phone all the reading list is get lost

(I'm not familiar with Wikipedia-app code, but taking a look on the code it seems to require a medium change in ReadingListData.java as well as developing backend and expose it in api.php)