Hi!
Also, there should be some way of doing queries that don't run on WDQS already, i.e., there must be something that times out now but can be done with ldf in a reasonable time [1]. Or are federated queries the main goal here? (that's still useful, but I hope that WDQS will also support a whitelisted set of external endpoint at some time)
Yes, the plan is to have a whitelist of SPARQL endpoints for which we allow federation queries. I was going to post about it in January when everybody's back from vacations :)
The use case for LDF is both running long queries and federation. The first use case of course would benefit from good SPARQL engine running on a machine with decent connectivity. So server-side JS or Java should probably fare better.