If he fails to return to India on time for the first Test as well as for future matches, it would be a huge loss for England, which is dependent on the player for his bowling. He is one of the best spinners in the world and in India, he could be the person that the English team would look to make the all important breakthrough, when it is required.
Indians are known to be the best players of spin bowling, but they have also faltered against quality finger spinner. Though, it might make life easier for the Indian team, but it is the ardent cricket fans who would lose out in a close contest.
But, Swann is not the only player that holds a great importance in the series for England, as they have players like Kevin Pietersen, skipper Alistair Cook who need to tackle the Indian bowlers and especially the spinners, Ojha and Ashwin who hold the key for India as well. The English team is gradually getting acclimatised to the Indian conditions after playing some practise matches, which will definitely put them in good stead ahead of the crucial Test series.
The Indian team may be favourites for the series, but they can't take it easy against their opponents. The Indian team also has a number of less experienced batsmen such as Kohli, Yuvraj and Pujara in the starting 11 and those experienced players are also not in good form, which includes the likes of Sachin, Sehwag and Gambhir. So, everything is not rosy, if the English bowlers come up with their best game.
But, all in all, the four-match Test series is not only going to test the Indian side, which will be minus Laxman and Dravid in Test matches. These two players held the Indian team together for a number of years in the middle order alongside Sachin Tendulkar, but their retirement has left a vacuum in the Indian middle order. It remains to be seen how these players cope against the English bowling line up.