Even in Generation V, the Sleep status ailment does not give a speed penalty to the afflicted pokemon and escape rates are not dependent on anything but both combatants' speed values. The only status ailment that affects escape rates in any way is Paralysis, and that's only because it confers a speed penalty on the afflicted pokemon. And even then, Generations IV and V are a long, long, long ways off - the devs themselves have said in the past they're not currently worried about those generations right now, and I don't recall them ever saying they wanted to make the game mechanics themselves radically different from how they are in the game. We have Generation III type mechanics regarding physical and special attacks in place, for example, even though in Generations IV moves are split up within types into physical and special moves. That change actually has precedent in the games, but, again, the devs have stated they currently have no plans to make that change.
That wouldn't even be an example of straying away from the design of the games. What chance does a mechanic with no precedent in the games have of being implemented?