This article by Tim Dexter of BI Publisher name and fame just tells in between the lines that all eBusiness Suite reports will be ported to Fusion. What is in fact the same as saying that Fusion is Apps 13, an evolution from R12, not a new game.
So the good old per_all_assignments_f will still exists. Maybe with a good looking UI on top of it, which passed for the first time an usability lab. Skip the last part, I'm asking too much.
SOA only matters at the back end side, not at the front end, despite the Web 2.0 vague.