react-redux-saga-router solution

Routes.jsx

import Router from 'react-redux-saga-router/Router'
import Route from 'react-redux-saga-router/Route'
import * as actions from './actions'

const updateState = {
  article: article => actions.setCheckoutStateToBuying(article)
}

export const Routes = () => (
  <Routes>
    <Route name="welcome" path="/welcome" />
    <Route name="purchase" path="/buy/:article"
      updateState={updateState}
    />
  </Routes>
)

WelcomeScreen.jsx

import Toggle from 'react-redux-saga-router/Toggle'

const PurchaseToggle = Toggle(state => state.checkoutState.status === TRYING_TO_BUY)

class WelcomeScreen extends Component {
  render() {
    return (
      <div>
        <PurchaseToggle component={ArticlePurchaseBlock} articleId={id} else={Welcome} />
      </div>
    )
  }
}