I was told that the Specialist Games moulds will be replaced and things will be made in resin, but not until their current moulds for metal wear out- so it may not happen for quite a while.
I heard this from a GW store manager, so take with the appropriately lethal dose of salt...
Having seen the resin models, I'm not particularly looking forward to WM scale resin models (bubbles, huge amounts of flash, easily broken pieces and warping/ models splitting).