An issue that comes up repeatedly when a company is considering changing its logo:

What about the expense of redoing everything (shirts, truck signs, business cards, etc. etc.) with the new logo?

That can turn a relatively minor redesign into a major expense.
The answer is two-fold:
1. A logo redesign should rarely be revolutionary. Almost always it should be evolutionary. That means the new logo is recognizably just a new version of the old logo.
You see this very commonly in consumer products. Pepsi’s new logo is an example.
Which takes me to the second point.
2. If your new logo is recognizably a version, modernization or upgrade of your current logo, you DON’T have to change everything all at once.
Pepsi for example is not using their new logo everywhere and in everything, at least as yet.
So you do your redesign, and, over time, you get it into use. When the shirts wear out, you replace them with shirts using the new logo. When you need to reprint the brochure, it gets the new logo. And so on.
This is VERY workable and it is critical. Most people are discouraged from needed logo redesigns by this exact issue.
Don’t be discouraged. A new logo can be a great upgrade of one’s marketing.