The game isn't popular enough for counties to spend hundreds of millions of pounds upgrading their grounds, and there's no sports that can fit onto a cricket oval to help cross subsidise improvements. The ground development that's happened in the last 10-15 years in Australia has basically been driven by AFL, not cricket.
The costs of upgrading are not as high as that. The Lords plan had included lots of internal and external upgrades beyond simply boosting capacity. Several apartment buildings behind the two stands on either side of the media centre, restaurants and hospitality boxes as part of the stands were also part of the plan. Anyway, I am not talking about all counties, perhaps a few of the test grounds. I think 40,000 is a realistic target for Lords, the Oval and Edgbaston. Surrey quite often sell out their T20 games at the Oval. Also, bigger grounds could perhaps put a stop to the constant rise in ticket prices, to a level only the type of crowd you get at a Lords test match wouldn't have a hesitation paying.
Let's do some basic maths. Lords will have seen 120,000 pass through the gates the first four days of this test match. 30,000 times 4 days, which equates to gate revenues of £4.8m if we total the number of people by £40, which I am using for the average ticket price for a day's play. We are going to exclude members from our calculation for the sake of simplicity.
These are just gate receipts. I am going to discount other revenues, like catering, merchandise, etc made by the club during the test, which can be similar, or even exceed gate revenues, during big international days.
Let's say we had a capacity of 40,000. 40,000 times 4 days gives us 160,000 total passing through the first four days, instead of 120,000. 160,000 times £40 = £6.4m.
You have approximately £1.6m from gate receipts over the four days by having 10,000 extra capacity. Higher capacity will also bring in higher non-gate reciepts. And even after costs associated with manning the higher attendance, the extra revenues will outweigh the extra costs.
And before you say Lords wants to keep a ground feel, they were pretty adventurous when they commissioned the 'spaceship' media centre for the 1999 World Cup. I think these two stands would have made the ground look awesome, and it would have looked great on the TV. But the members weren't going to benefit much from the addition, so they scuppered it.
http://www.architectsjournal.co.uk/...0825_Lord_s_Herzog_Picture_007_compressed.jpg