To generate test cases for the "Deadlock Detection" problem, we'll write a function that creates random instruction sequences according to the given constraints. Each sequence will contain a mix of digits ('0' to '9') and 'u', and will always end with 'u'. Additionally, we'll ensure the number of datasets is varied and adheres to the provided constraints.

Here is the Python code to generate such test cases:

```python
import random
import string

def generate_instruction_sequence(n):
    # Generate a random sequence of digits and 'u'
    sequence = []
    for _ in range(n - 1):  # n-1 because the last character must be 'u'
        char = random.choice(string.digits + 'u')
        sequence.append(char)
    sequence.append('u')  # Ensure the sequence ends with 'u'
    return ''.join(sequence)

def tcgen():
    datasets = []
    num_datasets = random.randint(1, 50)  # Generate between 1 and 50 datasets

    for _ in range(num_datasets):
        n = random.randint(1, 10000)
        s = generate_instruction_sequence(n)
        datasets.append((n, s))
    
    # Add the terminating zero
    datasets.append((0, ""))

    return datasets

# Example usage:
def print_test_cases():
    test_cases = tcgen()
    for n, s in test_cases:
        if n == 0:
            print(n)
        else:
            print(n)
            print(s)

# Uncomment the following line to print generated test cases
# print_test_cases()
```

### Explanation
1. **generate_instruction_sequence(n):**
   - This function generates a random instruction sequence of length `n`.
   - It ensures the sequence ends with 'u'.
   - The rest of the sequence is filled with randomly chosen characters from digits ('0' to '9') and 'u'.

2. **tcgen():**
   - This function generates a random number of datasets (between 1 and 50).
   - For each dataset, it generates a random sequence length `n` (between 1 and 10,000) and a corresponding instruction sequence.
   - It appends a terminating zero dataset to indicate the end of input.

3. **print_test_cases():**
   - This function is used to print the generated test cases in the required format.
   - It iterates over the generated datasets and prints them appropriately.
   - Uncomment the call to `print_test_cases()` to print the generated test cases.

This generator will help in creating diverse test cases for the "Deadlock Detection" problem, ensuring a thorough testing process.