I had an idea for a change to safeguard.
You use points earned through the rounds to buy weapons, attachments, perks and killstreaks.
You could set it so that instead of your weapons gaining levels as you play you make the gun stronger by spending points on the weapon stats and attachments. You'd also be able to buy killstreaks from the assault and support lines of the killsreaks and these killstreaks would stay with your guy till you bought different ones but you would still have to complete the required kills to use them.
This was a thought I had to give a little change up to the safeguard mode so that the game doesn't get boring by doing the same thing over and over again