You seem quite certain considering you clearly don't know who will and will not play - just like everyone else here.
Free agency is not done at July 10 - it lasts well into the start of the season, with end of the roster players (like some listed above) bouncing from team to team, camp to camp trying to secure a contract. Further, many free agents who do sign early, but with new teams skip NTs as they need to get settled into a new city, new team, new coach, system, teamamates etc.
You seem unaware the tremednous pressure NBA players are typically under to NOT play FIBA. From clubs, coaches, GMs, agents even family (weddings, births, sickness etc.). Sure a club here or there might actually be supportive of young, non-core players playing FIBA - but any star under a big contract or highly valued young player on their cheap rookie contract , usually everyone in their circle is trying to disuade them from playing..
It is ok to admit there is uncertainty and you just don't know anything here. None of us do...