I haven't researched this subject in any depth, but my impression is, whenever a company changes its focus, it still takes ages for it to be reclassified.
I noticed this especially in the case of small companies that chase a dream from biotech to gold explorer to oil explorer to Rare Earthers back to some high-tech gizmo.
It may be different for, say, the Top 500; you would expect them to be somewhat more "established" and continue to pursue one and only one track.
Furthermore, if you like me trade predominantly on Technicals, it doesn't really matter where a stock gets its lollies; as long as the chart says 'Buy' or 'Hold' - that's what matters most.