I don't think the new signing rules will affect either player. If they're determined to move, they'll threaten to sign elsewhere with no compensation and then their current team will max them out and do a S and T. Either that or they'll decide to take shorter money to go where they want. Both guy has banked big money already (D Ho $100m, CP3 $80m, not counting endorsement dollars).
If Cuban can jettison Shawn Marion for expiring contracts, Dallas will be in position to sign both of them. A team of Howard, Dirk and CP3 would be a big time contender. ATL has room to sign both, and also has a big time asset in Horford if the Hawks wanted to pair their on UFA, Josh Smith, with the FA duo.
Both player is in a very good position to determine his future. Staying put is a great option as is both of those FA scenarios.