Once earned, the points will be deposited into you Dividend Miles account with US Airways, so the points should be safe if you choose to close the card. Just be sure the points have posted to your DM account before closing out the card.
NFCU Flagship $32K | NFCU Cashrewards $42K | Discover IT $39K | SECU Visa $20K | Chase SW $24k | CSR $15K | Chase Bonvoy $11.5K | Chase Freedom $11.5K | Chase Amazon Visa 8.5K | AMEX Bonvoy $18.1K | AMEX Hilton Surpass $15K | AMEX Hilton Aspire $24.4K | AMEX Gold | Aviator Red $16K | Uber Visa 10k | Citi TY Premier $24.6K | BoA Premium Rewards 35k | BoA Cash Rewards Visa $31.5k | BoA Cash Rewards MC $23k | US Bank Cash+ $10k | USAA AMEX $6K | Cap1QS $11K | BJs MC $27.6K | Walmart MC $5.1K | Loft MC $25,000 | Macy’s Store/Amex $20K/$1K | BR Visa $10K | JCP $1K | VS $3.2K | Home Depot $5K | Lowes $8.5K | Target $14.5k
The DM points won't expire as long as there is activity on the account at least every 18 month - points earned or points redeemed.