Here’s the evaluation of each sentence:

1. **Correct**: "We are so excited about our trip next month to Austria. We will visit Vienna before traveling to Salzburg."
2. **Correct**: "Just a moment. I will help you carry these heavy bags."
3. **Correct**: "Thanks. I think my mother is going to like this cookbook."
4. **Correct**: "In the future, electric bikes will replace bicycles."
5. **Correct**: "As planned, Elizabeth will visit our franchise company in southern Turkey."
6. **Incorrect**: "Linh is so nervous! She is going to have a baby."

### Corrections Summary:
- **Sentence 5**: "our" instead of "the".
- **Sentence 6**: Change "will" to "is going to" or "is" for better clarity and correctness, depending on the intended meaning.