In its place, for slow connection or old browsers, will be a Google Maps Lite Mode, a slimmed down version of the new Maps that eliminates 3D and speeds Maps up generally.
The old Maps was a trusty companion and in its time, an incredibly innovative product. It still has features that will be missed. My top of list request for a feature to be added to the new Maps: The ability to show two or more sequential searches on the map simultaneously. It allowed me to identify a location in relation to other searches, useful in real life AND Local SEO.
But the old Maps had other capabilities as well that were useful, particularly in Local SEO work, that are still missing from the new Map. For example the ability to ferret out duplicate listings easily is now gone. (This makes Michal Cottam’s Page Finder more useful.)
The new Maps, in minimizing business listings, make them very hard for me (I am color blind) to easily parse on the screen. The new Maps makes reporting a problem less functional and accessing a G+ Plus page nigh on impossible.
To some extent I suppose that the era of importance of desktop Maps is starting a long decline into second class status as mobile Mapping takes all the glory. That doesn’t mean that the old Maps won’t be missed.