Getting fired as a Warrant Officer vs. Retiring?

No, those people talking got their wires all crossed. It's possible to have less than 20 years and be a two time non select and and be separated. In those cases if you have over 15 years AFS then you can request to stay till retirement. You would never be able to compete for promotion again and HRC will review your records before approving. Plus you would be entitled to Statutory Entitlement which would allow you to revert to your last enlisted grade and retire. You would receive the average of your high 3 years of pay for your highest grade successfully held for retirement pay.

FYI its not a CW2 thing, all commissioned officers eventually have to face the two time non select. All commissioned officers get two looks at promotion and must get promoted or separate out.

As for retirement, it's damn near impossible to take that away from a Soldier. If you're at 18 years AFS you will receive something called Sanctuary where you can become a fat turd and still retire while flagged. Short of UCMJ, you will be entitled to receive your retirement as long as you submit your retirement request.

As some others have said, once you get to 20 years you can retire regardless. Actually, you only have to make it to 18 years and then you enter sanctuary for the last two years, but will be required to retire at your 20 year mark. If you are a two time non-select prior to hitting 18 years AFS though you will be separated from service seven months after SecArmy certifies the board results. (e.g. Board convenes/adjourns in April, board results are typically certified in July or Aug, so separation would occur sometime around Jan-Mar.) Basically, you will probably need to make CW3 in order to retire. If you are young enough, depending how many years in service you have when you promote to WO1 you might be required to make CW4 in order to retire.

The one other caveat that no one has mentioned is Selective Continuation (SELCON). SELCON varies from year-to-year and you cannot request SELCON, but it can be offered to you. If you are a two-time non-select another board will automatically consider you for SELCON. Basically, it's saying you're not good enough to promote, but you're good enough to retain. SELCON varies widely with needs of the Army. If your MOS is under strength than SELCON is likely, if it's over strength than it's not. How long SELCON is offered for also changes each year. I've seen it offered for 3-years and also just 1-year. If you are offered SELCON than you continue to be considered for promotion and I have known multiple people that were selected for promotion while in SELCON. SELCON is nice to get you over that hurdle, or another couple years to get the OERs you need to get promoted, but basically it can't be counted on.

20 years is retirement. If you are passed over twice before you are eligible to retire, they can seperate you. I have seen people get passed over twice and booted out at 18 years.