SayHelloView.swift

/// Every view interacting with a `SayHelloViewModel` instance can conform to this.
protocol SayHelloViewModelBindable {
    var disposeBag: DisposeBag? { get }
    func bind(to viewModel: SayHelloViewModel)
}

/// TableViewCells
final class TextFieldCell: UITableViewCell, SayHelloViewModelBindable {
    @IBOutlet weak var nameTextField: UITextField!
    var disposeBag: DisposeBag?

    override func prepareForReuse() {
        super.prepareForReuse()

        // Clean Rx subscriptions
        disposeBag = nil
    }

    func bind(to viewModel: SayHelloViewModel) {
        let bag = DisposeBag()
        nameTextField.rx
            .text
            .orEmpty
            .bind(to: viewModel.input.name)
            .disposed(by: bag)
        disposeBag = bag
    }
}

final class ButtonCell: UITableViewCell, SayHelloViewModelBindable {
    @IBOutlet weak var validateButton: UIButton!
    var disposeBag: DisposeBag?

    override func prepareForReuse() {
        super.prepareForReuse()
        disposeBag = nil
    }

    func bind(to viewModel: SayHelloViewModel) {
        let bag = DisposeBag()
        validateButton.rx
            .tap
            .bind(to: viewModel.input.validate)
            .disposed(by: bag)
        disposeBag = bag
    }
}

final class GreetingCell: UITableViewCell, SayHelloViewModelBindable {
    @IBOutlet weak var greetingLabel: UILabel!
    var disposeBag: DisposeBag?

    override func prepareForReuse() {
        super.prepareForReuse()
        disposeBag = nil
    }

    func bind(to viewModel: SayHelloViewModel) {
        let bag = DisposeBag()
        viewModel.output.greeting
            .drive(greetingLabel.rx.text)
            .disposed(by: bag)
        disposeBag = bag
    }
}

/// View
class TableViewController: UIViewController, UITableViewDataSource {
    static let cellIdentifiers = [
        "TextFieldCell",
        "ButtonCell",
        "GreetingCell"
    ]

    @IBOutlet weak var tableView: UITableView!

    private let viewModel = SayHelloViewModel()
    private let bag = DisposeBag()

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return TableViewController.cellIdentifiers.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: TableViewController.cellIdentifiers[indexPath.row])
        (cell as? SayHelloViewModelBindable)?.bind(to: viewModel)
        return cell!
    }
}

The idea is nice, still It has one limitation, you are forced to use a concrete type of the ViewModel inside the View, you can't use ViewModelType.
So you can't reuse the view with other viewModels.
Example a view with a form for CreateAccount, EditAccount, they might look the same, but the viewModels are totally different.
Or you want to mock the ViewModel for UITests.

@georgescumihai, I believe this is just a simple implementation of the view. In his full post here, he has used the viewmodeltype protocol.

So in a real project, I guess we should declare the viewmodel as protocol instead of concreate type, then use DI to inject the viewmodel. With that, we can use different vms for the view.