How long can we realistically keep our stars? Like Stroud, Dell, and Anderson?

I know little about what goes on behind the scenes of the game. So forgive me for what is probably a dumb question. But if we've only signed them for a 3 year contract, does that mean whoever offers them a larger contract when those 3 years are up, we've lost them? I feel like with the texans being a less successful team than most, we'd be outbid pretty quickly no?