I have heard there is no High Year Tenure (RCP) in the National Guard. Does that mean a SGT can go all the way to 20 years, 30 years?

Actually the retirement age can be reduced. For every ninety days of qualifying service, you can collect retirement three months earlier. See below for details.

http://www.arpc.afrc.af.mil/ServiceCenter/Guard-ReserveFactsheets/FactSheets/Display/tabid/310/Article/580954/reduced-retirement-age.aspx

thanks but that does not apply to national guard. Also, those years are defined as active duty service. So doing the points/360 everyone should make 20 years reserve

I agree with SGT Peters, this AR may only apply to ARNG personnel (active service is defined as service on active duty) who are AGR and other selected Title 10/32 personnel. There is probably an NGB regulation this is covered under.
What the purpose of the 2016 RCP Policy Memorandum was to implement RCPs that are consistent for EMs serving on active duty across all Army Commands. The policy will apply to SMs serving in the RA and to USAR/ARNGUS who are serving under the AGR Title 10 programs. It does not apply to USAR/ARNG members who are mobilized, assigned to IRR, M-Day status or a TPU (troop program unit).

Sgt (Join to see) - Ah, then I stand corrected. Damn my not reading that fine print.