Bowling is a worry in every condition. While the spinners are doing okay now against Australia, it's mainly because of the current Australian batters' inexperience in handling good quality spin bowling. They don't get to face such bowlers in their domestic matches just like our batsmen don't get to face fast-bowlers with 140+ kph and swinging and bouncing the ball consistently. Do you remember how badly Ashwin and Ohja did against Cook and KP in the England test matches? So, Indian bowling (both fast bowling and spin bowling) is in bad shape for all conditions, and we will have to use the batting domination to compensate for the weakness in bowling. This is what the Indian teams in the past 20 years are doing. Fast bowlers like Umesh Yadhav are looking good, but are breaking down after every 2 matches. Can we now salute someone like "Kapil Dev" for his fitness even though we did not have so much of professional coaching and fitness training for cricketers those days?!
And another important factor is the arrival of T20 cricket. With so many T20 leagues around the world (IPL, BBL, SLPL, BPL, etc, etc) and each one of them paying the players handsomely, where's the motivation for young cricketers to learn the skills for the test cricket (which is now only for purists). The cricket coaching manuals are now being re-written. I will not be surprised if people start with reverse-sweep or a paddle-sweep in coaching in the days to come. Playing across the line is not a sin these days. Hence, these are not considered ugly shots. Where is the motivation for players to learn the skills to excel in the test cricket. All three forms of cricket now demand different skill sets in batting and bowling these days.
We can't blame the players for this. This is how the game is evolving now. Just imagine that if someone is willing to pay me 20 to 30 times more than my current salary for the same job I do now in another company for part time (only 1 day a week), what motivation will I have to excel in my current job working for 5 days and getting the current pay (which is 30 times smaller than what I will get paid in the part-time job). This is the reason people like Chris Gayle, Shane Watson, etc who are best T20 cricketers in the world (earning millions of dollars in a year for playing only for few days of cricket) are struggling so badly in test cricket. For example, Ashwin bowled more number of balls in just one Chennai test couple of weeks ago compared to the number of balls he will bowl in the whole of IPL season. Compare this with what he earns in one test match vs one IPL season, the difference is probably $500K or more. With this commercialisation, it will be very difficult to develop cricketers like Rahul Dravid or Amla or Ricky Ponting in the future. So, in summary, test cricket will continue to suffer, and get degraded or revolutionised into a different ball game in the future. So, we can not probably see one country dominating the whole world in test cricket in future (like the West Indies of 80s and Australian teams of 90s / 2000s). Every team may do well in their backyard and will continue to struggle in alien conditions because players don't have time and motivation to practice those skills any more.
Finally, more than all the above factors, there is one factor or one person who contributed to the down-fall of Indian cricket now compared to 2/3 years ago. It is the great guy called "Gary Kirsten". I think the difference between the current team and the team 3 years ago is "Gary Kirsten". We are currently lacking a strong coach and mentor who is able to get the best out of every player in every condition, not only with his technical skills, but using his strategic, leadership and man-management skills. Gary was able to get the best out of every player in the Indian team starting from seniors like Sachin / Rahul Dravid to young players like Virat Kohli. Even bowlers like Zahir Khan excelled under Gary's leadership and mentoring. This is how India was able to win the world cup and also achieve No.1 status in test cricket. The slide started as soon as Gary left the team. This is also evident in the current progress shown by the SA team (coached by Gary). The South Africa team has now attained the No-1 ranking in test cricket and are performing well consistently compared to what they were 2 years ago (with "chokers" tag).
I would like to sum it up by saying that my other favorite topic of "Leadership" and "Mentoring" is becoming more vital in professional cricket (and other sports also) these days to not only eliminate the technical flaws, but to enhance the mental state and motivation level of every player to achieve their best. I wish our own puriests like Rahul Dravids take up such jobs and become "Gary Kirstens" to keep Indian cricket flying high in the future!