In multivariable analyse, one of the important thing is the multiscale relation between variables. So for separating the spatial signal in its multiscales patterns, I use a wavelet and a multifractal filter on fast Fourier transformation (Integrated Spatial and Spectrum Method for Geochemical Anomaly Separation. Qiuming Cheng, 2000. Natural Resources Research, Vol. 9, No. 1). it is not very complex procedure, so i imagine that it will be easily to incorporate in arcGIS.
If the geostatiscal interpolation could take a cont of multiple anisotropies it will be very good.
If the geostatistical could be use in real 3D data with a similar interface like geostatistical extension it will be great.
And the last one. Can I dream of the day when all ArcGIS tools will work in the real 3D data.