I am a huge fan of Hive Keychain and I see a need in continued development and support for the browser plugin, especially in light of security.
Yet, as some of you know, I've been working on Hivewallet.app since August 2018, a dedicated app for iOS and Android which since Feb 2019 supports the formerly known as "Steem-Uri-spec" which offers exactly this support of key storage and signing of "signer requests" from both QR code and "hive://"-formed URI's from other mobile apps and "callback" to those apps. See the announcement about that "steem-uri-spec" here: https://peakd.com/utopian-io/@roelandp/steemwallet-update-v1-1-2-supporting-the-steem-uri-spec-for-signing-and-broadcasting-many-steem-chain-operations-without
Next to this mobile-app signing support, HiveWallet.app supports Keychain for Mobile already for browser based apps / sites through its integration of your Hive Keychain code in the dedicated dapp browser.
Concluding: I would love to fund continued development of the Keychain browser plugin, but I find it a though vote for a competitor on HiveWallet for mobile :). Obviously more apps in this space is great for competition, yet I would be basically downvoting my own initiative by voting for Keychain for Mobile.