Caution is warranted for any Navaid shutdowns
"Is this jumping the gun?" Likely for most cases, YES - it is jumping the gun.
The human factors interfaces with most (if not all current) low end GA RNAV systems (and many RNAV systems even in BizJets) is still marginal, if not even awful, making them difficult and vulnerable for any serious IFR IMC use. Until and unless these RNAV systems (e.g., GPSs) have their HF user interfaces substantially improved in later generations for serious IFR flying, except for air carrier aviation that uses modern exceptionally good FMSs with RNP, and aids like ILS and GLS, ...it is a very risky proposition (safety wise) to shut down any significant number of classic Navaid facilities that are currently being used by low end GA.
That's why it is so critical that GA finally get access to low cost high quality RNP based FMS like navigators soon (driven by a GNSS + low cost inertial component engine), and be able to dump this current generation of very difficult to use GPS panel mount navigators (WAAS and LPV are virtually useless), that no amount of initial or recurrent training can ever adequately satisfy, ...short of a pilot staying current by having to fly with them for hours every every single day.