We aren't talking about using a SD card for RAM. The SD card would be used to store the blockchain, update the blockchain with new blocks, update the unspent outputs each block, and bootload code segments of the bitcoin binary. Typically, flash memory is rated between 100,000 - 1,000,000 write/erase cycles (2 - 19 years if cycles happen every 10 min) and that's always writing the same segment over and over. With intelligent disk management to avoid "hot spots," this could be greatly increased. So I would expect even low-grade memory cards to last many years.
But skooter you don't really care about what we are talking about anyways, as can be verified by your post history as a troll and the glaring red warning in your profile.
Trade with caution. User interested in generating double spends and willing to share profits with miners to defraud others.
This is why he was negative trust rating. That doesn't tell you if someone is a troll or not.
Also the blockchain has grown over the past years but it will be growing at an increasing rate.