Making Percona/MariaDB/MySQL better at sharding, and supporting complex queries (with MPP capability, window functions, CTE,etc.) would really compete with an enterprise DB, with RedShift, and with Fabric. Shard-Query can greatly outperform both the enterprise MySQL Infobright (and MC ColumnStore) because it parallelizes operations differently, and supports horizontal scale-out over more than one node (which IB does, and CS does differently).
So what about group replication? I'm very much interested in group replication plugins. Using the GR plugin interface in combination with a rewrite layer that sits outside of the parser, it should provide notifications for transaction events and row changes which a sharding layer could act on appropriately to replicate or distribute data. It would coordinate distributed transactions. This would provide a layer to compete with Fabric. If I were to contribute such a layer it would of course have OLAP support. This would work with all storage engines and push down operations in a more optimal way than other distributed MySQL solutions like MC ColumnStore.
Making it so you can run SQL in the server should be a priority, in my opinion, as well as implementing a rewrite interface that is outside of the parser. I can commit to contributing this new rewrite interface to Percona/MySQL/MariaDB (whomever wants to implement it) through a relatively simple patch to MariaDB and MySQL (Percona Server is similar enough to MySQL such that the MySQL patch should apply cleanly or close to it).
With those capabilities I can implement Shard-Query inside of the server. The company that I am in the process of joining will support these changes, and will be responsive to bug reports, etc. I want to stress that operating in the free market to support extensions and plugins to open source software does not represent "competition". MariaDB can't use their non-compete clause to prevent me from operating in the ecosystem, as I would be unable to obtain any job in the marketplace. That represents unfair competition. You can't prevent me from practicing my profession. Shard-Query (WarpSQL) is engine and server agnostic as long as the server conforms to the pluggable API which WarpSQL uses. In order to prevent any possible perceived conflict of interest, or perceived competition, I won't provide any patches for columnstore, which is a separate MySQL fork maintained by MariaDB Corporation, than MariaDB itself, which is overseen by the Foundation.
Let's have a peaceful and community, and let's make MySQL much better at complex queries.