It's hard to predict prices far in advance, but $3500 invested every year for ten years would seem to yield the ability to pay for breakfasts and upgrades (confirmed at the time or reservation, not based on availability just before arrival) during short vacations.

It might be called lifetime Plat, but in ten years Starwood could be acquired by Hyatt, out of business totally, devoid of any loyalty program.....or they could redefine "Plat" to be below Gold. Note also that lifetime Plat is currently only PlatMinus with no suite upgrade certs unless you ALSO do 50 nights per year. I'm not sure whether the credit card nights in your scheme count for either lifetime or the 50 nights needed for the suite certs, which would be irrelevant for alofts anyway and to use them even for a minimal suite upgrade would require staying in a more expensive brand. Note that the suite certs expire so you can't save them for ten years.

However, your calculation neglected the points that would be earned by all your excess aloft nights, which could be used to pay for some of those nights with points or cash and points, which would lower your $3500 per year estimate.