Online wallets (it's only really blockchain.info) cannot alone compensate for the decline, and nobody was able to tell me if electrum clients would show up or not or what their numbers are. There isn't 'something else' than that. Plus the decline started to manifest before those 2 came up.
Why is it so hard to accept that bitcoin is loosing excess userbase?
Multibit wouldn't because it doesn't host the entire blockchain, I don't know about electrum. Cold wallets/Paper Wallets/Online Wallets/Smaller Clients are all becoming very popular, and most all of those things don't count for full nodes. Bitcoin isn't loosing its userbase, just look at the forums as an example:
A steady rise in threads, posts, etc, and a steady amount of users coming in every month. Plus the forums aren't everyone, there plenty of non members that use bitcoin.