I think the red and white tape may be marking out the extent of the future tiger enclosure extension. Work on the extension, new dens, indoor viewing, outdoor viewing and climbing structures is due to start in September 2018.
Indeed. I don't know how plausible it is, but what if they linked the tiger enclosure (by tunnel or extension) into the back wall (which is not listed) of the right hand Tecton, so it straddles the ex-polar bear Tecton. Now that would be impressive and provide a huge increase in space for the tigers.
However, that's probably wishful thinking and a very long way in the future considering all the plans they have in the pipeline.