I think the worry about OC causing new signs to go up is overblown, for the simple reason that there's been a big public shift in opinion about guns since 1996. Most people at least know someone who carries regularly, even if only unlicensed car carry.
If OC were legalized, 30.06 as currently written wouldn't apply, because it specifies "concealed handgun". Gunbusters signs might apply to a non-CHL, if they were deemed to be "sufficient notice". Non-CHLs would run the same risk of missing a small "no guns" sign and being charged with criminal trespass while armed, which is a Class A misdemeanor, that CHLs faced the first two years of the program.
30.06 could be modified to include OC (which wouldn't be good for CHLs carrying concealed), or it could be left alone and a new trespass notice created for OC.
My preference (aside from completely deleting PC Chapter 46): Change 46.02 to specify that it's an offense to carry a concealed handgun without a license; and, modify 30.05 so that trespass while armed is not an enhanced penalty. (Since there's nothing lower than Class C misdemeanor, perhaps specify a maximum penalty of a $25 fine.)